Today my felicia 1.3 failed its mot on the emissions. Recently the car had occasionally felt a bit uneven on acceleration, as if the fuel mix was either a bit rich or lean. This was put down to the lamba sensor which has recently been replaced and the engine has felt very smooth since it was replaced.

The details for the emissions test are:

Fast idle test Fail

Engine Speed 2573 rpm Pass

CO 2.97% Fail

HC 141 ppm Pass

Lamda 0.92 Fail

Second fast idle test Fail

Engine Speed 2576 rpm Pass

CO 3.08 % Fail

HC 142 ppm Pass

Lamda 0.91 Fail

Natural idle test Pass

Engine Speed 782 rpm Pass

CO 0.47 % Pass

Scan shows 2 faults: 00537- Oxygen Sensor Control and 00525- O2 Sensor voltage low. The scanner I have is very basic Autel VAG305.

Hope I haven't missed anything out. Many thanks.

Edited 12 January, 201115 yr by DISC BRAKES

you normally get the 'sensor voltage low' code when the heater element in the tip of the lambda sensor has gone open circuit, basically the heater element burns out.. sadly there's probably not an aweful lot you can do about it except chucking a new sensor in there... avoid the cheapo ebay ones like the plague.. i got an NGK one from my local motor factors for £50 a few months ago

or if you need to do it on the cheap just swipe one off a scrapper to get in through the mot

Are all the NGK lamda sensors the same model or do they vary?

Would the faulty 02 sensor cause the high CO level on the emissions test?

Thanks

Edited 13 January, 201115 yr by DISC BRAKES

yes high CO is caused by running rich

edit: the 1.3 and 1.6 both have the same sensor

Edited 13 January, 201115 yr by TeflonTom

Have ordered NGK lamda sensor to pick up tomorrow.

Lamda sensor fitted. Passed MOT with flying colours.

Thanks for the advice Teflon Tom

glad you got it sorted out