Hi all

Anyone have any suggestions as to what could cause the following?

If I roll down a hill in gear (she's a manual) then the CEL will come on reporting error code 41 (LAF Sensor) if I roll down the hill in neutral then she's fine.

Going by the black on the pipe at the rear I would say that she is running rich a lot of the time, there are a couple of other abnormalities that might be related... if I am stopped on a hill the tickover is about 700, as soon as I drop the hand brake and I roll forward the revs climb to about 1100.

I've cleaned filters, replaced plugs, checked the timing etc and I am at a loss.

The obvious answer is to replace the sensor but it is the 5wire version (that costs an arm and a leg) and I suspect that it is reporting the mixture being out range rather the sensor being faulty (same error code for both).

The car is stock standard and still doing about 35mpg around town, but it can't be good for the car to be running like that...

ANY help/suggestions will be gratefully received.

 

41 appears to be a heater code which is pretty conclusive the sensor is bad. US versions have a 4-wire sensor though so you may have a different system than that.

Black stuff just on the inside of the tailpipe is fairly normal. My car has it with no CEL and good mileage. If you have black stuff on the back of the car or visible smoke while driving (have someone follow you in another car and watch) there's a problem.