weird behaviour with engine warning VR V6

[pecksterism99]

This behaviour is very puzzling ...


If I drive off from cold, and get straight on the motorway and just keep going, the engine warning light doesn't come on.

But in normal driving around town, it'll come on after about 6 minutes or so.

Checking the codes, I get the following:

12 (OK!), 43 (knock sensor) , 44 (oxygen sensor) & 56 (lean under load).

Seems to me if those three faults are genuine, the engine light should always come on ...

Anyone struck this one before?

[PRAVX II S]

Change the O2 sensor mate.

[dave-the-sparky]

the reason it comes on after it warms up is when it is cold it is in open loop and the PCM ignores the oxygen sensor readings. it could also be a vac leak after the throttle body that shows up as oxy sensor fault.

[pecksterism99]

Yes it was the oxygen sensor. City fuel consumption now down from 15.5 to 11 L / 100km!

[matty m]

replace oxygen sensor

[pecksterism99]

Yup - that's what I did and it brought fuel consumption down by nearly a third, and engine warning light is now off. Thanks for the tips.