Lambda Sensor - Control Limit Surpassed

[tonytiger 0]

Problems with my VR today :( (Sorry about the length of the post)

 

Drove to work this morning - no problems.

 

Had to go out at lunch time (about 3 hours later) - seemed okay initially, while under 30mph, but then tried to accelerate steadily upto 50pm and it wouldn't pull/rev very well. Then the more I put my foot down, the less power it seemed to have and the revs just started to fall. Pulled over and let it idle for a few minutes and revved it a couple of times then set off again. Didn't seem too bad but just took it very steady.

 

Going home (about 5 hours later) - seemed a little rough and lumpy when started but set off okay again. It was only when trying to accelerate upto 50+ that it was really noticeable again. Acceleration was very poor below 4k rpm, but seemed to go like normal above that. Further into the journey I flicked the MFA onto mpg and it was under 20. I reset it and at a steady 70mph it still only showed 20mpg (and falling!). Reset it a few times and it was consistently poor (and sometimes under 15mpg). I'd normally average around 30 over the whole journey.

 

Plugged VAGCOM in when I got home and actually got an error (I've had pretty much the same problem before but not got any errors):

00537 - Lambda (Oxygen Sensor) Regulation
08-00 - Control Limit Surpassed

From what I've read on other threads, I assume the car was in 'limp home' mode and just chucking loads of fuel in. Above 4k rpm (at least with my foot on the floor), the lambda reading is ignored so the car behaves more like normal. Have I got that right?

 

I watched the readings from the O2 sensor in the measuring blocks (with the car running) and found that the reading varied from just below 1.0 up to 1.203 (which seems to be the limit). I actually just did this at weekend too (exciting life I have) and the values were between 0.899 and 1.055. Is this measurement in Volts?

 

I know it looks as if the lambda needs replacing, but could this just be the symptom of something else? I'd rather not replace the lambda if this is an electrical fault or something. I thought they normally just died and gave back a static reading - that doesn't seem to be the case here. Would an ecu reset help?

 

A couple of things which may or may not have an impact here:

- the car does smoke (blue) from time to time on startup and over-run so it needs a head rebuild (and hopefully nothing more).
 
- it stalls (a lot) - cleaned the isv, replaced the dashpot, cleaned the throttle body (as best I could), replaced the isv - made no difference.
 
- at the weekend I ran a wire from the o2 sensor to inside the car, ready for an AFR meter. Could this have a caused a problem? I also found that the connector end of the wiring on the o2 has been replaced (the last few inches - different colour wiring but the the right connector)
 
- I think there may be a leak in the exhaust but don't know where - could be near the front

 

I suspect I'll have to replace the o2 anyway (to eliminate it if nothing else) in which case does it matter whether I get one from ECP or is it best to get a VAG one?

 

Really appreciate any thoughts and advice you can offer.

 

Cheers,

Tony.

[tonytiger 0]

I've just looked in the Bentley manual at the DTC chart for the O2 sensor (should have done this last night :oops: ) - does 'Control Limit Surpassed ' sound the same as 'Regulating Limit Exceeded'?

 

If so, then I've got a few things to check and the O2 sensor itself may be okay:

- O2 heater defective
- Exhaust system leaking between cylinder head and cat (is there an easy way to check?)
- Misfiring
- Intake air system leaking
- Injectors malfunctioning
- Fuel pressure too low
- Hot wire for MAF sensor not burning cleanly
- EVAP canister purge regulator valve stuck open

 

Not sure I'm capable of testing everything myself though, so if it's not something very obvoius it'll have to go to the garage :(

 

If the car's still running the same today, would it be okay to drive to work and back (total of 80 miles) or is best left at home? Would I do it any damage, or is it just a case of it using lots of fuel and not being very pleasant to drive?

[tonytiger 0]

Just been out and started the car and idled it for a while - no problems this morning and the O2 sensor's not showing any faults and readings seem okay again.

 

Think I'll chance driving it to work again today - and perhaps see if I can get a new set of plug leads to stick on.

 

The last time I had this problem (possibly everytime I've had this problem) was under the same cirumstances - drive to work, and then go out at lunch time (a few hours later), so car wasn't completely cold. I'm sure there's a clue there somewhere as to what's wrong - what's the link between the that and the list of things to check above?

 

Why don't I get the problem all the time?

[Andy T 0]

I had a very similar problem 2 weeks ago with my G60 and it turned out to be the lambda probe.

 

When it runs bad & bogs down, is there any black smoke from the exhaust? If the lambda has gone you usually get black smoke when you accelerate, and your tailpipe would of turned black after a few minutes of this!

 

Best thing to do is unplug the lambda probe harness at the connector when it happens again, if it runs well with good mpg (limp home mode is safe fuel settings and won't chuck too much fuel in) its got to be fuel related, most likely the probe.

 

How do you mean the connector has been replaced, has it been grafted in with new crimp terminals? the wiring colours are different from one side of the connector to the other, this is normal.

 

If it does turn out to be the probe, use a VAG one (or a VAG one sourced through GSF/ECP if they sell them) don't use cheap generic ones, they don't always work properly and are made from cheaper materials so only last a year or so!

[tonytiger 0]

I haven't noticed any black smoke while driving it, but did get some last night whilst idling it on the drive - revved the engine a bit and got quite a cloud - it's the only time I've noticed it though. The exhaust is sooty though (and has been for a while, just don't know how long).

 

Regards the wiring, basically somebody has chopped the connector off the end of the lambda wiring and soldered a replacement on, so there's several inches of wiring at the end which is a different colour. From the connection on the engine mount onwards (to the ecu presumably), it looks like normal. Don't know if this is significant or not - it's been like that since I got the car last October. Have to say though, I don't know if it's a genuine VAG one or not (though the wiring looks the right colour up to the point that it's been cut).

 

From what you've said about limp home mode, presumably it wasn't using that. So what would happen if I just unplugged the lambda completely? Would this put the car in safe mode, and drive better (and more economically)?

 

My concern over replacing the sensor is that it's not the sensor at fault - it's one of the other things listed in the Bentley manual. Ideally, I'd replace the coil pack, the leads, the sensor, the MAF, the throttle body and the hoses - but that'll cost a fortune and still may not fix it.

 

I'm getting the exhaust checked on Saturday, hopefully that'll find something.

 

The only other thing I was thinking of doing till then was (possibly) replacing the ignition leads. Just been quoted £109+vat from VAG - is that likely to be the newer, poorer leads, or the original red Berus?

 

Oh, nearly forgot, the problem did come back on the way to work (after about a mile), but just carried on (gently).

[Andy T 0]

From what you've said about limp home mode, presumably it wasn't using that. So what would happen if I just unplugged the lambda completely? Would this put the car in safe mode, and drive better (and more economically)?

 

Yes, if you unplug it, the ECU realises its not there, and defaults to a stored fuelling map. I ran it like this for a week, I got better MPG than usual and it ran almost normally.

 

Like you say, you are getting some black smoke when you rev it, it points more and more to the lambda probe, or water temp sensor, its unlikely to be the plug leads. running rich will eventually kill the cat too.

 

If the loom has been cut, I'd say its definately running a cheap generic probe - best to get rid of it and replace with an OE one if you want the best perfomance/mpg/reliability out of your car. The guys checking your exhaust should be able to tell at a glance which type it is - a genuine one will be stamped with the VW logo, and have flexible aluminium tube protecting the wires where they are close to the exhaust system.

 

The other thing to check is the continuity of the connections - I found resistance in the circuit from the earth wire from the loom to the bolt on the engine mount. I cleaned up the connection but it made no difference - The whole engine has some resistance to ground so there must be a bad earth somewhere. I wired a seperate earth wire from the engine mount to a stud on the o/s suspension turret which gave a really good earth.

 

If you unplug the lambda connector, then start the engine, you should be getting 12v across two adjacent pins on the 'engine loom' side, this is for the probe heating. you could also check for a circuit between the two pins on the 'probe' side.

 

Andy

[tonytiger 0]

Andy T, thanks for the advice. I'll check what you've suggested and try running without the lambda plugged in. Hope it stops raining soon.

 

Cheers,

Tony.

[tonytiger 0]

Well, I've disconnected the o2 sensor as advised and it does seem just about like normal. :D

Took it for a run and fuel economy looked good (normal) again - at least until I floored it! Looks like economy REALLY suffers in this situation if driven hard. I'll find out tomorrow anyway going to work and back. It'll be interesting see if it cuts out as much too.

 

I'll get the sensor changed as soon as I can and take it from there.

 

Thanks again Andy T, as I didn't think I'd be able to drive it again until it was fully fixed.

[Andy T 0]

Good stuff. Just looked back through my notes when I was pricing up a lambda sensor, Euro car parts do a VR6 genuine one for £82.25 inc. vat (might be slightly cheaper than dealers?) and GSF do a 'best quality' VR6 one for £68.15 inc. VAT, but you'd have to check what make it was (genuine ones are Bosch)

[n8047035 0]

hello all,

 

Where abouts do i locate the lambda sensor cos i need to check mine out. I know this is a really dumb question but i need to locate it so that i can unplug it and see if it makes any difference to the running of my car.

 

Thanks

 

Amrik

[Andy T 0]

Errrmm, what car have you got?

 

You need to just unplug the wiring connector, which is on the rear engine mount on the G60, and probably in a similar place on the other engines.

[tonytiger 0]

Problems continue :(

 

I had a new lambda sensor fitted on Thursday evening. Seemed okay on the journey home from the garage (though it was probably only 5 to 10 minutes).

 

Decided to do an ecu reset yesterday before I drove to work. I followed the instructions I found on here somewhere, and the rest of the journey to work seemed fine. However, the journey home was not quite so good. Car drove okay, but didn't seem quite right (though certainly nothing like as bad as it was in the first place). Plugged it into vagcom when I got home and had 3 faults showing:

 

00525 - Oxygen Sensor (G39)
[list:f4ea7]03-10 - no Signal - Intermittent

00537 - Lambda (Oxygen Sensor) Regulation

08-00 - Control Limit Surpassed

00533 - Idle Speed Regulation

10-10 Adaptation Limit Not Reached - Intermittent

[/list:u:f4ea7]

 

Cleared those faults and drove the car again last night, and this morning, and now just have one fault code showing:

00537 - Lambda (Oxygen Sensor) Regulation
[list:f4ea7]08-00 - Control Limit Surpassed

[/list:u:f4ea7]

This is the original fault, so having just forked out 70quid I'm no further forward :mad: Looks like I'm back to the original list of suggestions in the Bentley manual:

I've just looked in the Bentley manual at the DTC chart for the O2 sensor (should have done this last night :oops: ) - does 'Control Limit Surpassed ' sound the same as 'Regulating Limit Exceeded'?

 

If so, then I've got a few things to check and the O2 sensor itself may be okay:

- O2 heater defective
- Exhaust system leaking between cylinder head and cat (is there an easy way to check?)
- Misfiring
- Intake air system leaking
- Injectors malfunctioning
- Fuel pressure too low
- Hot wire for MAF sensor not burning cleanly
- EVAP canister purge regulator valve stuck open

 

I've run the DTM Output test in vagcom with no obvious problems - heard the injectors click, and the isv, and EVAP valve (though I haven't had the pipes off this).

 

Also, I did think that running with the sensor unplugged had solved my stalling problem (didn't have any problems the first day or two) but that came back as well. So I'm no further forward there either - will stall with or without the sensor.

 

Couple of questions on the ecu reset -

- Is 4 minutes disconnected long enough?

- Would that purge the stored fault codes?

 

I can't afford to replace everything in turn until the problem's fixed, but equally I can't afford to run the car for long when I'm only getting 260miles out of 51litres :shock:

 

What I should I do next? Suggestions please.

 

Thanks.

[dr_mat 0]

Could well be your MAF not reading correctly too. The MAF and O2 sensors make up the basis for most of the engine's decisions about fuelling. If the MAF is lying about incoming air levels, but the O2 sensor (lambda) is working fine, it's 50/50 as to which error code comes up. I'd suggest you beg/steal/borrow another MAF and try resetting the codes again before checking VAGCOM. Seemingly perfectly ok MAFs have often proved to be the culprit for running problems. Even Bosch have trouble figuring out if a MAF is truly ok or not..

4 minutes disconnected should be enough. I think bentley says 30, but that's overkill... Yes, if it's genuinely reset the ECU it also loses record of any stored faults.

[Andy T 0]

Did you clean up the lambda probe connections & earths? I'd definately run a new earth cable from the terminal on the bracket to somewhere good on the chassis.

[tonytiger 0]

The O2 connections have been cleaned, but hadn't thought about a new earth. I'm going to have a close look at the MAF, see if the wires look clean or not - hopefully there'll be something to see.

 

I've spent a few minutes watching the readings from the lambda on vagcom, and it looks like it actually gets reasonable values initially until the car's about up to normal operating temperature. Once the sensor reading goes out of range, if I rev the engine and then close the throttle sensible looking readings are shown from the sensor again briefly - but then over a few seconds the value gets progressively higher until it's out of range again. I suppose this is probably what you'd expect - but I'm sure there's a clue there somewhere, just can't figure out what it is.

 

I've read numerous other threads about testing the MAF, but I don't understand why it can't be tested with a multimeter. While searching for further information on them, I came across the following which I wasn't aware of (hadn't really thought about it either) :

 

The current required for heat­ing provides an extremely precise - albeit non-linear - index of mass air flow. The system's ECU generally converts the sig­nals into linear form as well as assuming other signal-processing duties.

 

So the output values should form some form of curve (I think). But if the value's are out of range surely that can still be measured? It's a shame the values from the MAF aren't shown in vagcom (at least not that I could find).

[dr_mat 0]

The ECU ignores the lambda during the cold-start cycle, and overfuels in an effort to heat the catalyst. Any lambda readings during the first two minutes are completely pointless...

Does vagcom show the voltages from the lambda or some other indexed value?

[tonytiger 0]

Vagcom shows some other value - typically between 0.8 and 1.2. I've just had the car running on the drive, vitually from cold, with vagcom monitoring the values until the car had warmed up quite a bit. Haven't had a good look at the log file yet, but the o2 values definitiely look okay during the warm up period. Oddly, once the sensor did start to go out of range and would reach a value of 1.203 it would sometimes jump back to 1.0 (not sure if this is supposed to be stoich or not) without any throttle change and then climb back up to 1.203 again

 

I'm hoping to fit an AFR meter very soon so that I don't need vagcom running all the time.

 

I know it could still be the MAF, but I'd rather not replace that just yet - need more convincing.

[dr_mat 0]

If you have the opportunity to replace the MAF on a "try it and see" basis, it's got to be worth it. The readings you're getting seem to be on the high side, but I've not looked into what VAGCOM normally reports, so I can't say for sure.

Presumably you've checked for air leaks right through the system, from the MAF to the catalyst..?

[Kevin Bacon 5]

Ignore VAG-COM's lambda readings. A serial or USB connection cannot keep up with the rapidly fluctuating voltages from an O2 sensor. If the voltage is moving, the lambda is working and all you need to know.

 

To test it, you should really use a high impedance voltmeter (at least 1Mohm) to check the probe. It will sit at 0.45V for two minutes as Matt said, during it's preheat cycle, but then it should fluctuate up and down constantly from 0.1v to 0.8v. If it's stuck permanently at 0.45v..... the probe is dead or not connected properly.

 

Meter's red wire into lambda white wire and meter's black wire to earth (not the lambda earth) on the engine block somewhere.

[tonytiger 0]

I've now fitted a home made AFR meter (as per the instructions on this forum - thanks Kev). 8)

 

I've not had chance to drive the car since fitting it, but have run it at idle for a few minutes. Don't know if I've done something wrong, but the meter starts with all the lights on during the initial couple of minutes, then starts to fluctuate. When you say it should 'fluctuate up and down constantly', do you mean several times a second or slower than that? Mine appeared to get to 0.8v and sit their a second or so, then drop quickly to 0.1v and again sit at that for a second or so (but obviously the car was no where near warmed up). I'll get a better idea tomorrow of what's going on when I drive to work.

 

As for checking for leaks, well I've had a look as I did think that was most likely to be the problem but I haven't found anything. Covering the exhaust tailpipe briefly did cause pressure to build, but is there a more thorough way of checking?

 

Thanks for the advice so far guys. I'm sure I'll get to the bottom of this in the end with your help - though no doubt it will involve parting with a load of cash. :roll:

[Kevin Bacon 5]

On the AFM, it should sit half way across the LED array (if in dot mode - easier to read at a glance) for a couple of minutes, then it should go mad and constantly flick up and down when on part throttle - closed loop mode. When you plant the throttle, the AFM should sit at 0.8V until you back off - Open loop mode.

 

From what you've described, your probe sounds fine.

[tonytiger 0]

Interesting drive to work. AFR initially showed readings as expected.

 

From cold, showed about 0.4v for a couple of minutes. Then shot up to 0.8v and started flicking up and down (quite quickly). If came off the throttle, the lights would extinguish. All going well so far, but had only used part throttle. Once the car had warmed up I gave it full throttle, and this seemed to be when things started to go wrong. Can't remember most of the lights came on or not at this point, but when I went back to part throttle the lights weren't flicking up and down any more. Tried this a few times but with the same result. Not really sure whether the problem was caused by use of full throttle, or just that the car had reached a certain temperature.

 

Cruising at part throttle, at any speed, gauge only ever showed 0.2v or 0.3v. WOT didn't change this - gauge display stayed the same. Fully closing the throttle did cause the lights to extinguish, but still never came back above 0.3v.

 

About 30 minutes into the journey, I pulled into the m/way services to see what happened at idle. No different - still only 0.3v. Continued on to work, but stopped again (for petrol this time) on the way. When I started the car up again, things did look any different - but was the sensor going through it's warm phase again at this?

 

Stopped watching the gauge, as I was only a couple of minutes away from work, until I noticed it flicking up and down after a quick blast on WOT. Seemed to be functioning like normal again, but didn't have chance to try it any further.

 

So, I'll try not to use full throttle at all tonight and see if the same thing happens. Hopefully, this should show whether it's temperature or full throttle related.

[tonytiger 0]

Just got in from work (via the pub).

 

Started off from work only using part throttle and keeping revs below 3000 rpm. As with this morning, everything seemed okay initially (though it seems to vary whether all lights are on only half for the first couple of minutes). However, once the oil got to around 80'C the gauge stopped going past 0.3v again. Gave it full throttle, at low and high revs - no difference. Same all the way home. Car was also very 'juddery' tonight too at times, probably only when on light throttle at any rpm.

 

A couple of miles from home, I stopped at the pub. :) Was pleased just to stop the car at that point, as it was getting worse and worse to drive (though perhaps that's partly weather related as it was raining).

 

Left the pub after about 90 minutes. Car was still fairly warm, and oil was soon up to 90'C again but everything was okay again. Gauge flicked up and down when expected and WOT did show about 0.8v. However, after 5 minutes or so, things started to deteriorate again. Gauge didn't show a sudden drop to 0.3v but the upper limit seemed to steadily decrease, so instead of flicking up to 0.8v and down again it would only go to 0.7v, then 0.6v etc, until wouldn't go past 0.3v again - it also got slower too.

 

Now I'm just really confused. Is it a temperature related issue or not? The problems all seem to start at a similar time into the journey, which also happens to be at a similar oil temperature. Perhaps it's related to the intake temperature on the manifold, but I've not been able to run vagcom while driving though so don't know what the intake temperature is in each situation.

 

Is it still likely to be the MAF? What else could fail/deteriorate at temperature but not result in any error on vagcom? Is there any thing I can rule out? Being as I'm getting through so much fuel but the lambda is usually seeing lean - would I be right to rule out fuel supply problems?

 

I really need to disconnect the lambda again, to improve driveability but instead of unplugging it I think I might just cut the wire to the ecu. That way I'll still be able to monitor the output on the AFR and see how it compares.

[tonytiger 0]

Very interesting drive to work this morning. Stopped for petrol, about 10 minutes after setting off and filled it up this time (only put £10 in the last twice). AFR gauge had shown no real problems up that point, despite car being fairly well warmed up and having used full throttle a few times, though it looked like the highest value shown was already starting to drop.

 

After filling up with petrol, continued on for a mile or so (still no problems) and then stopped so that I could disconnect the MAF at idle. Car stalled when I did disconnect it so that does seem to be working okay.

 

Continued on again (onto the motorway) - still no problems. Lights on gauge were flicking up and down at part throttle, 8 were lit at full throttle, and none lit on closed throttle.

 

Some miles on, I did notice that the 8th light wasn't coming on anymore, and a while after that the 7th light was only lighting dimly.

 

Pulled into the services - things generally still okay. Stopped car and took petrol cap off for a few seconds, refitted then continued to work. 7th light started to light fully again, but 8th still wouldn't.

 

So, although I'd previously assumed that there was no problem with the fuel supply, it's now a possibility that it is the problem after all. Could I be getting a vacuum in the tank, giving problems with the supply? Could it be the fuel pump? It seems too much of a coincidence for it not to be fuel related - especially as the car got worse and worse to drive last night as the fuel level got lower and lower (nearly to the red).

 

What I don't understand though, is if it is a problem with the fuel supply why am I getting through so much of it? I'd assumed that meant it couldn't be a fuel issue - or is it because the fuel supply is erratic?

 

 

After I'd filled up, the car didn't stall once either (but perhaps that was just coincidence too).

 

I'm feeling somewhat happier now anyway - it looks like a solution may not be far away.

 

I'll probably replace the fuel filter again anyway, but if I do have to replace the fuel pump, does it matter whether I get genuine vag one or not?

[tonytiger 0]

Time for an update.

 

Replaced the spark plugs (which weren't looking too good) but this didn't really make much difference. Was going to replace the fuel pump, but changed my mind as not really convinced that's the problem.

 

Problems continued, car often unpleasant to drive. Nothing was showing on vagcom (other than sometimes getting the same message about the lambda) until 15th September, when I got the following error:

 

00515 - Camshaft Position (Hall) Sensor (G40)

30-10 - Open or Short to B+ - Intermittent

 

Finally felt hopeful that the car could be fixed (without too much cost). Had a quick check of the wiring but couldn't find any obious problem so ordered the part from local dealer the Friday of that week, told part would be in Saturday morning. Excellent I thought, can change it Saturday morning and test it over the weekend. Went to collect the part only to find that the wrong item had been sent (right part number on bag, but wrong part) I was not happy, to say the least - especially being as it was going to be Tuesday afternoon before I could get the correct part. :mad:

 

So, that Tuesday I left work early, collected the part and went home to fit it. Parked on drive, went to get changed came back to car and !$%! £^&*$%£ !"£$ - couldn't open drivers door, handle had broken - bloody typical :x Did fit the cam sensor that night still though. The journey to work the next day was great - AFR meter still showed a possible problem, but car was great to drive. Journey home was okay too. Progress at last. :D

 

That same week I also managed to get a MAF off Ebay (to try a swap in case mine was duff), and collected it in person. The seller turned out to be CorradoVR6-n.o.s on this forum (or rather was on this forum - he's now swapped his vr for a scooby). Got talking about the problems I'd been having with the car and immediately suggested changing the cam sensor (spooky!), but also suggested removing the isv noise damper to stop the stalling.

 

So, last Sunday I swapped the MAF, removed the noise damper and fitted a new air filter element (and a new drivers door handle). Now, having done all those things at once I can't say for sure what's made the difference (and I really should try putting the original maf back on), but bugger me :!: the car's not stalled since :lol: I've made every effort to get it to stall - dipping the clutch for a while whilst driving, coasting up to junctions etc, but it just wouldn't. It's been a long time (probably around 8 months or more now) since I could drive the car without constantly having to worry about it stalling and it's great. :D :mrgreen: So big thanks to CorradoVR6-n.o.s for that. :thumbleft:

 

Now I've only got one possible problem again - the AFR sometimes still just sits at 0.3v (weak mixture) and will not move. I've found over the past couple of weeks that everythings usually okay on my journey to work until I get stuck in queues with just a couple of miles to go. Sometimes it's okay once I'm moving again, but sometimes it's still stuck when I start my journey home. This must surely be heat related - just still can't work out what it is. That would also explain why I had such a problem back in August when the weather was at its hottest. I've not found anything else on vagcom so I think this will now have to wait until after the head rebuild and I get the injectors serviced (got a spare set for that). I'm not noticing any economy or driveability problems though, and if it wasn't for the AFR I'd not suspect a thing.