Hello everyone wondering if anyone can help I've got a 2007 ford fiesta st with the mountune mp185 kit on and I've been having some problems with it to start with I've got these dtc codes.
P1131. Lack of ho2s11 switch indicates lean.
Then I got u1039.
Then today I've taken battery off for 2 hours then put it back on and got these codes of the on broad dtc thing.
e510 c100 c121 e197 e200. The engine management light is on along with abs and had the service light come on as well. That went of again I've reset the codes and they have come back on again.
Now the car will tick over fine then it will start to rev a little bit then back down to the point it almost cuts out which it has done before. Also it sounds like it's sucking in air for around belts had it check said it was ok. It sometimes cuts out when I'm coming to a stop or trying to park ECT.
What I've done so far is clean the inlet. checked for leaks with easy start nothing found. Looked for pipes that looked odd didn't see anything also changed no1 lambda sensor. There was a plug that wasn't pluged in so I pluged it in and nothing changed looked like it was to do with the power steering. There was all so a very small leak that was just before the cat on the wels that was leaking and I mean small so I sorted that and it's still the same. I hope someone can help me with this thanks in advance.

Ps sorry if anything is wrong on what I've wrote I'm very tired and still at work for 5 more hours