Evening all,


This car has MOT emission problems and presented codes relating to fuel trim and lambda sensor fault. PO125 also appeared (insufficient coolant temperature for closed loop fuel control). I have scanned the CTS at 98c, coolant fan cuts in and I have measured the voltage at the sensor at 0.48v. This sensor appears to be ok. The other fault codes have been cleared and do not come back. PO125 clears and then comes back after 10-15mins. Now here is my query. Lambda sensor sometimes works and sometimes not. When all is well the emissions are perfect. I think the lambda sensor and CTS are OK but there is a soft-ware problem with the ECU. Your thoughts would be appreciated.

Regards

Pete M