Threw a code

[clipse-T]

Went to autozone this morning to check my CEL..and i threw a P0170 : Fuel Trim malfunction..does anyone know what this could be? They had a sheet there telling what the causes of that could be and it included:

MAS failure..but i just replaced that not too long ago
O2 sensor failure
Fuel injector problem
ignition misfire/vaccum leak

Basically it said that i was running rich or lean. My question is could i have a leak on where my exhaust manifold stud broke off making me run rich..causing for the CEL to come on? Please help.

 

[FORMONTOYA]

The fuel maps for cars have a "fudge" factor that tags along, basically a +/- over what it expects the fuel trims to be. If for whatever reason the ECU "sees" that the trims have gone outside this tolerance range for a certain period of time (don't know what length it is), the ECU will throw this code.

The car can throw the P0170 code for the above mentioned reasons. It can also throw this code for reasons that you mentioned........exhaust leaks pre-O2 playing havoc with the sensor. It can also throw this code if your injectors are not compensated for correctly after an upgrade.