HI Guys,

 

New to the forum, so apologies if this is in the wrong section.

I have a 53 reg Ford Fiesta. The EML light is on and no matter what I do it comes back on.

Taken it to a garage, where they put it on there machine, fault code of the lambda sensor.

Replaced both front and rear sensors, which seemed to fix the issue. However a few days later it came back on. Took it back to the garage, and they replaced the cat and changed the lambda sensors again. Once again ok for a few days but then came back on. 3rd time back to the garage and they took it to an auto electrician who diagnosed the same issue (sensor).

Light is still on and not sure what else to do.

Any suggestions or help would be appreciated.

 

Thanks

 

When they changed the sensors do you know if they checked the wiring for damage?

10 hours ago, robbo651 said:

Replaced both front and rear sensors, which seemed to fix the issue. However a few days later it came back on.

Like mintalkin say, wiring (or connectors) is one of the remaining possibilities.

Other possibles are leaks in the exhaust system before the cat, or

Faulty replacement sensor (it does happen!)

The exact code(s) might help. Typically DTCs can be signal errors (open circuit, short circuit, out of bounds), and range or functional errors (Signal not consistent with expectations / other readings).

O2 sensor range errors could actually be caused by quite a number of engine faults that upset the fuel / air mixture, but are not directly detectable by the pcm.