MOT emissions failiure

[swfblade 0]

Had her MOT'd yesterday and failed on the CO reading. Was WAY out on the CO readings (5.5%+) and also slightly low on the Lambda (around 850). Was aware that she's been overfueling for a while, but havent had chance to get it looked at.

 

Was thinking that it might be something like the MAF sensor / Lambda Probe? Is there anything else that this could be caused by?

[TIMMYVR 0]

Could well be the lambda sensor mate if its overfueling. running to rich so emissions will be high.

[dr_mat 0]

Usually the lambda when it's overfuelling that badly.

[CazzaVR 0]

Blimey! 5.5% CO! I've just failed on 0.33%, and failed the re-test on 0.31% :mad: Slight mixture prob- everything else was spot on. They're being kind and giving me another re-test on Friday as it was soooo close. Going to my local specialist on Wednesday to get it sorted.

[swfblade 0]

So how much a Lambda likley to cost me?

 

Im pretty confident I can fit it myself, so just really need an idea of parts cost.

[CazzaVR 0]

£70? Maybe less. Have a look on GSF and ECP.

[swfblade 0]

Just had a look on GSF's website and they have lambda probes for £49+VAT. But they also have "LAMBDA PROBE, General Use x WIRE UNIVERSAL" where x is a number between 1 and 4. (How maths was that statement?!? :lol: ) & a "LAMBDA PROBE TOOL 22MM".

 

Does that mean I need to get the wire & tool as well?

[CorradoVR6-Turbo 0]

It will be a 4 wire probe,and cheap replacement Probes will need to be joined up to your existing lambda probe wiring,get genuine as its better sampling and gives you better fuel consumption aswell. You just need a 22mm spanner and maybe,if your lucky it will come out without stripping the threads.

 

Also make sure you have no leaks in the exhaust system as this will throw the lamda readings off.

[swfblade 0]

so you're saying dont get the one from GSF?

 

I assume by genuine you mean get one directly from VAG? How much are they likley to be, as my old copy of ETKA (couple years out of date now) says that a lambda will set me back £125?!?

[swfblade 0]

oh and would a Golf VR lambda do the job?

[CorradoVR6-Turbo 0]

Get the direct replacement from GSF but not the crap universal one,don't know if the VR6 will work or not mate.

[PhatVR6 0]

try changing the oil too

 

if it's overfuelling that much it'll have contaminated the oil, which can also throught the CO readings high.

 

My missus golf just failed last week, just done the exact same thing after reading the tip in the haynes manual.

 

also, when you take it for the test, give it a damn good high speed high revs raggin before you get there, it'll also keep the CO down.

 

if the car is stood for a while and tested from cold it's bound to fail. so never leave your car with them all day for an MOT. book it in at a set time, then rag it there so it's hot when he tests it.. this also means the guy might burn his hands if he looks too close, serves him right, swines.

[double-6s 0]

It will be a 4 wire probe,and cheap replacement Probes will need to be joined up to your existing lambda probe wiring,get genuine as its better sampling and gives you better fuel consumption aswell. You just need a 22mm spanner and maybe,if your lucky it will come out without stripping the threads.

 

Also make sure you have no leaks in the exhaust system as this will throw the lamda readings off.

 

Yeah my blue one has a hole in the downpipe - emissions were a touch high ;)

[Davesmi 0]

Another one is to put some petrol additive in and then cane it to the mot station it certainly worked on my g60.

[CorradoVR6-Turbo 0]

Davesmi, Welcome.

[swfblade 0]

try changing the oil too

 

if it's overfuelling that much it'll have contaminated the oil, which can also throught the CO readings high.

Yeah, she's actually due a service as well, so Ive booked her in with a m8 who works at Audi.

 

also, when you take it for the test, give it a damn good high speed high revs raggin before you get there, it'll also keep the CO down.

 

if the car is stood for a while and tested from cold it's bound to fail. so never leave your car with them all day for an MOT. book it in at a set time, then rag it there so it's hot when he tests it.. this also means the guy might burn his hands if he looks too close, serves him right, swines.

LOL! :lol:

Funnily enuf, the car had just been ragged back about 50 miles. Was playing games with a brand new caddy! Dam those things are quick!

 

Cheers for the advice tho, i'll get the oil changed b4 i take her back.

 

Oh and surely if the xzorst had a leak, that would have shown up on the MOT? Or am I giving testers too much credit there?!? lol

[swfblade 0]

ok the lambda was replaced....no difference. On closer inspection the garage found that the 3 wires to the probe were all broken!

 

So, 4 new tyres (went for 215/40 17" Toyo Proxes T1-R's this time round), a new windscreen, new lambda and a rewire and ive got my MOT.

 

Thats got to have been the most expensive MOT Ive ever had! Especially as the last one was 6 months ago on my 20yo Polo, that failed on a wiper blade! lol