Car running badly and stalling. Ran code reader- codes 137, 141 and 0300. Replaced O2 sensor #2. still get random misfire and engine light came on after erasing codes. Ran code reader again, code 0300. What could it be? What causes random misfire?
02 Sensor and Random Misfire on 2003 Saturn Ion
Asked by for the 2003 Saturn Ion
Random misfire is caused by anything that would cause an engine misfire. First, at times, software issues will cause it- requiring a calibration update. Secondly - tune up items - spark plugs, spark plug boots. Third - the coil housing (secondary ignition). Fourth - fuel injectors. Fifth - base engine issues - like a valve issue in the head...although those usually show which cylinder on the test.
Thanks. I'll check back with you.
I had a coil die on me while driving once. When I replaced it with one from my parts car, I discovered something extremely valuble!!!! My car was a 1996 Saturn SL2. Parts car was 1997 SL1. Both have the same coil. And both had a ton of oil and dirt built-up between the coil and the engine block. I now have another 1997 SL2. Just bought it, only has 86,000 miles on it. It was starting hard. The odd thing was, it would start rightup after I would just turn the engine over for a second or two. It would also start easily after it was just shut off. I took off the coil tonight and found oil and mud. took it off cleaned it in the kitchen sink, PROBLEM SOLVED !!! Cleaning the coil should be part of routine maintenance for everyone. And, if you have a leaky Valve Cover Gasket, replace it ASAP. I will be doing mine today.