2008 GT is giving me code P0153

[Woody627]

Here's what came up for that code:

Definition:
H02S21 circuit condition (heated oxygen sensor bank 2 sensor 1)

Explanation:
The Powertrain control module uses the oxygen sensor to calculate the Air/Fuel ratio in the exhaust.

Probable Cause:
-O2 sensor defective
-Fuel system running very rich or lean - check other codes first
-Engine misfire condition - repair
-Fuel pressure very high or low - fuel pump or pressure regulator

This came on shortly before I deployed, and I did not mess with it. The car is heavily modified, and was most likely tuned (yes, I know it's bad that I don't know everything about it, but it was modded and then sold by a dealer). I had the car in for a cooling fan issue and they ran the diagnostic and all that. Would the dealer doing their test wipe a tune and thus cause a O2 code? I have not inspected the O2 sensors yet, but I will start there. Just wondering if anyone else has experience with this code and if so what fixed it for them. Also, I had put a new battery in when I got back and obviously this reset the code. I believe it came on after 9 days or so. I have not noticed any change in performance yet.

[Woody627]

Also, I have an appointment with the Green Valley Ford dealer, but they already said it'd be $115 to run their diagnostic test. I really don't want to do that, I just don't know where to take it if I don't find anything wrong with the O2's. Any recommendations for something like this?

[SloSVO]

depending on what was "heavily modified", the only way a dealer would wipe a tune is if there was an update.. but the tech would be the decision maker on whether to do it.. if he did and your car is "heavily Modified" then it would probably immediately run like shit... you have to see what your fuel trims look like, the voltage output and response time of the 02s, and go from there.. it could be as simple as the 02 sensor being done..

[Woody627]

Cool, I will check it out.

[Woody627]

Quick update, got a new O2 sensor from Ford, swapped it out, and reset the codes. The old sensor was cross-threaded, but I had the car and drove it for quite some time before the codes showed up, so I don't think it was an install problem on the original O2. When we turned the car on, it actually gave the original code plus an additional one, P0135 which is "Oxygen O2 Sensor Heater Circuit Malfunction (Bank 1, Sensor 1)", original is "Oxygen Sensor Circuit Slow Response (Bank2, Sensor1)". I cleared the codes so we'll see what shows up again and how soon, but seeing as how both sides have issues, where else should I look for problems? Or is this just a coincidence that both sides have issues? The car has about 61,000 miles on it now, and I just drove about 1900 miles to Wisconsin. The car got 26mpg according to the car's info panel, and I have not noticed any problems driving the car. I just have pesky codes that won't go away.

[Woody627]

Update: After the ~1900 mile drive home, I have had no problems and the car seems to be in perfect health. No codes at all.