2004 ford fiesta lx engine warning light

[fordfiesta]

The engine warning light came on- i had a diagnostics check- it showed up the oxygen sensor. This was replaced. Then about week and half later the engine warning light came back on and stayed on. Took for another diagnostics check showed up oxygen sensor and knock sensor. Anyone any ideas?

 

[Burnerman]

Has the performance of the vehicle changed? Often the lambda sensors indicate a fault that takes care of itself and the lamp goes out on its own accord. As for the knock sensors, thats a different matter. The thing is, we don't know if the fault was one previously stored or not - the ideal thing to do is to have all of the faults read, and then cleared.
John