I have a 2005 Mitsubishi endeavor with the following codes: P0431, P0174, P0421, P0171, P0304, and P0431 and I haven't the faintest idea what any of them mean. I have searched the internet with no luck and would appreciate any help that anyone can give.
I have a 2001 Mitsubishi montero limited. My car has generated a P0300 random misfire code 5 times since 12/22/2015. It always happens under hard acceleration (like an onramp to the interstate) after the car has been running for about five minutes. No other codes have ever been set. The car occasionally idles roughly. The spark plugs were changed 60,000 miles ago. The car has 113,000 miles. I am the first owner, and the car has been very well maintained. I will be replacing the plugs/wires. Any suggestions for troubleshooting?
P0171 & P0174: Both Banks lean. Check for vacuum leak(s) and perform a fuel pressure test. P0421 & P0431: Both cats below efficiency. This may be a result of the above codes. Graph/compare all O2 readings. Possible cat(s) damaged or O2 sensor(s) issue. P0304: Diagnose cylinder 4 misfire.