Hi. My wife's 2014 Citigo check engine light comes on. After its last service, our mechanic cancelled it, saying the fault says 'engine running lean'.

It's been fine 6 months, but now the light is on again.

Does the lambda sensor need replacing, or something else?

Regards

Stephen

I had this on our 2016 Citigo and it was fixed with a new O2 sensor.

I agree it could be the o2 sensor. Its likely to be the one after the cat. Check that you have no exhaust leaks as well as my sons fabia mk1 had similar problems. His exhaust was leaking at the flexi join. Not by much but it was enough to put eml on.

Alasdair

Thanks

We had this recently on my Wife’s 2014 Citigo, a friend cancelled the fault code but when it came to MOT time the car failed due to high emissions, we had the post cat sensor changed but unfortunately it failed it’s retest as the emissions were still too high, in the end we had to get the Cat replaced, with a new Cat it passed the MOT at the third attempt

Thanks. If the light comes on again, we'll try replacing the aft lambda sensor. It passed it's annual test yesterday showing Lambda 1.0, so it's not the cat.