3 cylinder 1.2 6V failed MOT on emissions

[gareth29]

Help, I'm trying to diagnose whats wrong here. Ive plugged in the VCDS and here is the screen shot of the fault codes and a pic of the O2 sensor.

http://i1349.photobucket.com/albums/p756/gareth291262/20170529_132714_zpsswtmpxmi.jpg (http://s1349.photobucket.com/user/gareth291262/media/20170529_132714_zpsswtmpxmi.jpg.html)

http://i1349.photobucket.com/albums/p756/gareth291262/20170529_131607_zpsctpyhceu.jpg (http://s1349.photobucket.com/user/gareth291262/media/20170529_131607_zpsctpyhceu.jpg.html)

I've tested for a supply to the heater and a supply to the sensor and these are fine. Also the resistance of the heater seems ok.
There is a grey/brown deposit on the sensor, but its not thick and Im not sure whether this could affect its operation.

On the MOT the details were:

On the 1st fast idle test CO was 0.88% and the limit is 0.3%. Lamda 0.982. HC 70 ppm.
On the 2nd fast idle test CO was 1.05% and the limit is 0.3%. Lamda 0.974. HC 28 ppm.
On the natural idle test CO was 0.39% and the limit is 0.5%.


Just whipped the plugs out so here they are cyl 1-3 left to right. No. 1 smelt strongly of fuel (faulty injector?) but otherwise they would clean up. I turned the engine over with the injectors exposed and the all seemed to be working consistently.

Not sure what all the deposits on no 3 mean - burning oil?

http://i1349.photobucket.com/albums/p756/gareth291262/20170529_191846_zps9lvxewdq.jpg (http://s1349.photobucket.com/user/gareth291262/media/20170529_191846_zps9lvxewdq.jpg.html)


I also checked the heater wire back to the ecu and there was continuity so all looks good there.

Do I just replace the sensor? or could it be something else?

Thanks for looking.

[Crasher]

16687 (P0303) - Cylinder 3 Misfire Detected
Looks like you have a problem with the rings on number three but start with a new lambda sensor and a set of plugs plus a set of coil packs would be sensible.

[gareth29]

Thanks, Ive put some new plugs in as that was quite cheap. Never thought about coil packs. Wasnt sure about the lamda sensor - am going to let the garage call that one tomorrow - was quoted £100 for an ngk one today so dont want to replace it on the off chance.

[Crasher]

Using your reg (ooooY) the system says your car uses Lambda sensor 03D 906 265 so I would use an NTK (aka NGK) 91967 which is also known as an OZA708-EE1 as this is what is fitted from new, most alternatives are universal fitments including Bosch. Euro Car parts do these NGK Lambda Sensor (http://www.eurocarparts.com/search/710444075)

[gareth29]

Result! It went in morning and passed without a glitch - so not sure what that says about the vcds fault code for the Lamda probe?

[Crasher]

It says nothing about VCDS, all that does is read what is there, monkey see monkey do. As a wise Austrian once said, “I’ll be back”

[FLAPPERJACK76]

Now its more like "oh my back" .

Sent from my SM-G930F using Tapatalk

[Crasher]

I know how that feels.....

[gareth29]

What I didnt understand about the vcds message was it was saying that the probe heater had an open circuit, which means that its bust. If the engine can get through its MOT, it cant be bust can it? Also I did check it with the meter and all appeared well.

[zollaf]

heater gets probe hot before engine does, keeps warm up emissions down, doesnt affect it once the zorst has warmed up and everything is working as it should.

[gareth29]

Thanks for that

[Crasher]

The heater is there to boost the ability of the sensor to work in lower EGT situations and it bring the sensor up to working temp very quickly from a cold start.