Faulty lambda sensor?

[paulvx220T]

With the engine warmed up the fault AFR456 bad comes up. The lambda sensor two is not varying in voltage when you put the engine under load it says aroun 0.3V. i can clear the code but it comes back after a few minutes and i have also noticed that the adaptives atart to run high on 456 going up to around 30%. Is a cause of this a faulty lambda sensor.

Thanks

Paul

[twinreal]

Hi Paul,
if you make a real time log, you will see if both lambdas are continously switching between 0V - 1V.
Should look like this:




Thomas

[paulvx220T]

Hi Thomas,
Lambda 1 is switching but 2 is staying around 0.3 volts. I have checked continuity and resistance on the both sensor heater wires and they are both 6.4 ohms.

thanks

[twinreal]

Wiring, plugs and signal earthing are ok ?
I unplugged my lambdas for testing something short time ago and the ecu didn't log a lambda fault, but AFR fault. So maybe it also can be a wiring problem.

[paulvx220T]

I was not able to start it for a an hour but it then started. Will a faulty sensor prevent starting?
Thanks

[twinreal]

I don't think so. You could unplug Lambda 2 (or both) and see if it starts better. You will then log an AFR fault on both banks and adaptives will be very high (maybe your 30%).
i would do the following steps (having a similar problem at the moment):
- check Lambda plugs for corrosion
- check the bulkhead connector to ecu
- as a last option swap the Lambdas and see if problem occurs on bank 1 (should definitely be a faulty lambda then).

Edited by twinreal on Friday 5th July 19:58

[paulvx220T]

I have resolved my sensor issue. Replaced the Lamda sensor but still had the problem. Started to check all earths by measuring voltage across battery terminals and comparing it with the voltage at various points on the chassis and engine block. There was 0.5V difference between the positive terminal on the battery and the engine block. The grounding strap between the engine and chassis was showing high resistance, cleaned all the terminals and re-checked voltages, now no difference between voltages. Connected the software and both lambda's are working also noticed that my throttle pots which used to vary by a few percentage at idle are more stable only varying by up to 0.3%.