I've been having this problem for a while now & it's doing my head in. About two months ago my car went into limp mode & was showing faults that where all pointing to the sensors & was saying the system was too rich at idle so I replaced the maf sensor, turbo solenoid & the map sensor which seemed to have cured it for abit but then the problem came up again so I replaced the knock sensors & same again was ok for a while until this morning when it went into limp mode & was pointing at one of the sensors & saying the system was too rich at idle. Has anyone got any ideas as to what this might be? I've checked all pipes for leaks etc & everything seems fine. Any comments will be appreciated.