xc90 T6 petrol auto throwing O2 sensor warning message

[MissSpentYouth]

Hi, I have a 2005 xc90 T6 petrol auto which is lighting up the engine warning light.

Code from Vida is - ECM - 280A front heated oxygen sensor (HO2S), bank 1 - faulty signal

Monitored the following on Vida -

ECM - Lambda control, bank 1 reads C/L at idle and when reeving but switches to C/L if you rev it up and then release the throttle ditto bank 2

ECM - Oxygen front sensor, bank 1 reads 1.03 at idle and stays about 1 if you rev it up but goes to 5 if you rev it up and then release the throttle. ditto bank 2 which reads 1.01 at idle

Is this normal going up to 5 when you release the throttle ? Could this be what is setting the warning light ? as I read that values over 4.8 can set the warning

[MissSpentYouth]

sorry that should read C/L going to O/L

I assume that means closed loop to Open loop control

[gmonag]

I would suspect the sensor, but check the wiring and terminals first.

[Rooster]

Has the engine been checked for air leaks, ie smoke tested

If not i would get it checked as if its got an air leak in intake system then it will upset air/fuel ratio and put lamba codes in,

Just because its putting codes in for sensor doesn't mean its faulty

[wilssp2009]

My t6 has been throwing up the an O2 sensor code for a while also even after replacement - how do I do this smoke test ??

[Rooster]

Any half decent garage should have a smoke tester,

Basically they remove intake pipe from maf sensor and plug a cone in its place and plug a smoke machine like what nightclubs have into it and fill system with smoke to detect leaks,

Google it, they are a great bit of kit