Error Code P0173-Fuel Trim Bank?
 

I got two error codes, P0173 and P0125. I thought the cause of the P0173 was the P0125. However the ECT is fine, and I just replaced the thermostats, coolent is full.

So now I'm guessing its the P0173 causing the P0125. Autozone can't tell me what a P0173 is for a mitsubishi is. However, for a Kia its a problem with Fuel Trim Bank 2. Whats a Fuel Trim Bank?

The following should help explain:

http://www.obd-codes.com/p0173

Yeh, it sounds pretty innocuous and can be a lot of things. It definitely is "heat" sensitive. I thought it was fixed as the light went out. However, after a long hard drive yesterday with the car heating up a bunch, the light came back on.

Wow the Mass Air Flow sensor is $300. Thats a lot to spend on a "maybe".... It doesn't make sense that the mass air flow sensor would work some of the time and not some of the time. I would think this particular part would be an all or nothing.

I guess I'll start by cleaning the MAF sensor. If that doesn't work, then I replace the O2 sensor.