Failed the MOT today, fast idle pass, natural idle, failed on CO, way way way above the acceptable tolerance, should be under 0.5%, reading was 2.64%.

I suspect the Lambda sensor needs replacing. Would appreciate it if you good peops could confirm for me. I'm doing an ECU diagnostic right now......

Car is a UK Turbo MY99

Cheers.

 

No ECU faults. As the exhaust is standard and it's running both cats I'm putting my money on the Lambda, going to pick up a Bosch LS02 now.....

.....anybody have any idea which wire goes where in the plug?

 

The smart money would go on the Lambda, particularly if you've got both cats on still.

Faulty Lambda's tendy to result in quite a lumpy feeling drive part throttle around the 3,000 rpm mark.

It's been a while since I've changed one, but IIRC it was relatively obvious which wire goes where. On a 3 wire sensor 2 wires are the heater and normally the same colour as it doesn't matter which way it goes round and the 3rd is the sensor wire itself. If you have a 4 wire sensor (the scoobs use 3 wire as standard) the the 4th wire is the ground.

 

Nice one, tis a 3 wire and have picked up a Bosch part. I have experienced a very slight lumpiness under light throttle low in the rev range so looks like this ties up, I guess that if the CATs were stuffed then the fast idle would fail also. Also I suppose that the ECU wouldn't pick it up (yet) if the Lambda sensor is still cycling, albeit slowly, and is on it's way out.

Ta for the advice.