Greetings all!

I have a 2006 Fabia 1.2. It failed emissions test with Lambda value 0.73 (a pass should be btw 0.97-1.03). I cleaned the map sensor and now the voltage of the O2 sensor in vcds reads 0.82v. Does anyone know if the voltage read corresponds to the lambda value (that means 0.82v = 0.82 lambda)? I am thinking the best start would be to look for vacuum leaks. Would anyone have advice in this regard?

Thanks,

Halse

Google images will show you lots of graphs of voltage versus lambda value and/or air/fuel ratio.

Does VCDS not show you some fault codes in engine ECU? Emissions (picture of engine) light on?

Only fault code that shows up is 16762 related to camshaft sensor

I pulled the camshaft sensor out to test it and it does react to create a signal voltage, but it could be that it does not send a strong enough signal

Or the timing chain has jumped.

That fault code isn't one that Google recognises. Please check for typos.

Correct the code is 16726, and yes I thought also about the timing chain as a possibility. Just in favor of ruling out the simple things first.

Is it the twin cam or single cam 1.2?

(Spark plugs vertical down centre of head in the former, angled out the front in the latter)

Not sure, will check the plugs later in the day. The model is Fabia Ambiente 1.2, variant SCBMEX01 and version NFM5FM52T037L13S0G.

Sounds daft but check the exhaust for leaks. My sons failed similar reading. Exhaust had slight leak at centre coupling (not enough to hear) MOT guy sealed it up and it passed straight away.

Alasdair

Here is what the engine bay looks like. Would that be a twin cam? My friend thinks it may be the idle controller valve that might cause the problem (not letting enough air through at idle). Otherwise will check the exhaust coupling. Apart from low lambda the CO emissions at high idle were measured to 8,7% (the limit for fail is 0,2%)

Yes, that's a twin cam.

This thread may be useful to you for checking the chain timing:

Has my timing chain skipped? Any easy way to check? - Skoda Fabia Mk2 (2007-2014) - BRISKODA