VERY High Emissions MOT Failure

[CazzaVR 0]

Well, been away for a few days and left the car with the local garage to do a couple of jobs + put it through its MOT. It usually goes through perfectly without advisories + the emissions are always very low. Phoned them quickly today to see how it was doing and it's failed. Apparently the CO is over 5% on fast idle! It passed on the low idle.

 

They've done a scope test on the MAF and it's fine. Gotta be the lambda surely?

 

Any ideas?

[dr_mat 0]

It's likely, yes, but there's only one way to diagnose this - and that's via the engine computer and VAG-COM or equivalent.

[boost monkey 0]

Ah you broked it mate, Better give it to me! :D

[CazzaVR 0]

Will try to pop over to the garage tomorrow and get it on VAGCOM.

 

Still skulking around on here then, Monkey-boy? :lol: I may be tempted if this MOT isn't resolved quickly!

[CazzaVR 0]

Bump- any ideas?

[Pete 0]

Is it driving ok? Smoke or caked exhaust tip?

 

Could be loads, lambda, throttle position sensor, plugs, dirty air filter.

 

Also check the air box/maf jubilee clips aren't overnight and wrinkling.

[CazzaVR 0]

The garage seem to think it could be something to do with the throttle body, ECU or MAF. It's had new plugs and I cleaned the BMC a few months ago. New VAG blue temp sensor a couple of months ago. Dunno if it's driving OK as I haven't driven it for a month. Was OK last time I drove it. Garage told me to call back tomorrow afternoon.

[swiftkid 1]

Have you had it on vagcom?

 

I'd go with maf first, they are always buggering up, when they go kaput the ecu goes onto a base map so still behaves similar. Unplug it when the engine is warm and see if anything happens. If engine note changes it would suggest it is working so maybe look towards lambda sensor and make sure the wires to the plug are not broken. First things first though, vagcom is your friend!

 

Has the performance or fuel economy changed recently?

[Pete 0]

I have a mint working 6pin maf for sale.

 

My vx220 was down on power the air filter was clogged, pulling in crap and the throttle body got crusty. Take the TB off and blast it with carb cleaner, but that shouldn't ruin the air/fuel mix, it's the sensor that would be the issue making the car overfuel.

 

VAGCOM will definitely help narrow it down.

[CazzaVR 0]

Nothing coming up on VAGCOM AFAIK. Done the unplug test on the MAF and it seems fine, but I know they can go wrong, but still appear to be working correctly.

[Harrier 1]

Have you tried the lambda yet ? would deffo try that first. I have a good spare if you want to borrow it to try.

[CazzaVR 0]

Thanks Daren, thankfully all sorted... Lambda.

[Tigerfish 10]

Looks like I've got the same issue. Mine has just failed on very high CO readings, HC's are fine :(

 

any brands of Lambda to avoid?

[GlosterOx 0]

Thanks Daren, thankfully all sorted... Lambda.

 

Good to hear Andy - What about the ABS Light?

 

Ian.