I had an exhaust leak from the passenger side header and had them replaced with a DC header only on that side. Now I have the car back and it runs like **** at low speeds and is now throwing that code. I know that the car needs to be tuned in order to fix it but is there any other way? Can't the computer adjust itself when you reset it since it detects its lean? The car was really cheap and I only threw the DC headers on their because I had them laying around from my last car 2 years ago so I can't justify spending $700 on a tune.

Also I have a feeling it was very stupid to have one side be an aftermarket header whilst the other side is a stock header.

 

Headers don't "add power", they shift where the engine MAKES power and that means you lose low end torque in favor of high end horsepower. That's probably why it feels like it runs like ****, because you gave up the low end grunt for some screaming high rpm power, but only on one side lol.

OBD2 scan realtime data (android app torque pro with a bluetooth adapter like the BAFX works) to see what your short term fuel trim STFT and long term fuel trim LTFT are sitting at as well as O2 sensor 1 data. That's the biggest issue with running dissimilar headers, one side might be lean and one side might be rich because the engine isn't adjusting each back independently (it is but it's overshadowed by a blanket of fuel trims), STFT and LTFT are blanket adjustments that affect the whole motor not just one bank.

 

So wouldn't resetting the ecu clear the LTFT and allow the car to readjust the A/F ratio? If not, is the only way to buy an osiris cable and DIY tune the a/f?

 

I would pull and inspect the plugs, they will tell you exactly what cylinder conditions are.