Hi, I have a 2002 Ford Fiesta Zetec and it has failed its MOT on the Offside Rear Exhaust emissions carbon monoxide content after 2nd fast idle excessive. The garage I took it to said they could not diagnose the problem and advised I book it into a Ford garage for diagnosis. In the meantime I thought I would try my local Kwik fit to which they carried out the following tests and could not resolve the problem:
1. Changed air filter
2. Fuel Treatment added
3. Lamda ( sensor 2 ) ( Rear ) changed: Reversed readings from CO high to Lamda high / CO low
4.Repaired broken pipe ( vacuum) from fuel rail
5. Refit clips to air filter housing and induction piping
6. Run OBD diagnostic ( no errors stored)

They have written on their report:
Vacuum noise coming from right hand connection of fuel rail. Maybe allowing excess air into return system

Any suggestions to what could be the direct problem before I put it into a Ford garage ?

Thank you
Vanessa

Hi,

Welcome to the Ford forum. Hope u enjoy ur stay here.

i would not trust kwik fit to blow up a pushbike tyre never mind work on a car,did they use ford lambarda sensors as some other make are not up to the job, find a good independant garage to give the car a look over, it will be cheaper than fords.

hmm, is the second (post cat) lambda sensor not just for diagnostic purposes? the pre cat one is what determines the mixture for the ecu?