How to solve the misfire detected in cylinder 3 (P0303)?
2 Answers
P0303 detected misfire in cylinder 3. First, check the spark plug, cylinder wire, and ignition coil, and replace the spark plug or ignition coil in time. For the maintenance of engine misfire, sometimes it is not possible to find the problem by only reading the engine data stream, and an oscilloscope is needed to further make a judgment. The following is the relevant content introduction: 1. The factors to consider for ignition include ignition timing, whether the spark plug is working properly, whether the resistance of the high-voltage wire is within the standard range, whether the ignition coil is working properly (whether the power line and signal line are loose). 2. Also check whether the engine control unit is working properly (including the signals provided by CAN data). It is recommended to use instruments for detection as much as possible.
Last time I encountered a misfire issue in cylinder 3, that P0303 code was quite annoying, but I managed to solve it by starting with the basics. First, I carefully inspected the spark plugs—sometimes aging or carbon buildup can prevent them from firing. I unscrewed them to check if the electrodes were eroded or cracked, and replacing them was cheap and effective. Then, I took a quick look at the ignition coil, pulled it out to test the resistance or listen for sparking sounds, and replaced it if faulty. I also checked for loose or corroded wiring connections, cleaning the plugs to ensure good contact. If the problem persisted, I had to measure the cylinder compression—there might be issues with piston rings or valves, requiring professional tools. Don’t forget the fuel system; clogged fuel injectors can also cause misfires, so cleaning or replacing them helps. Finally, I used a diagnostic tool to clear the code and test-drive to confirm the fix. Regularly changing the air filter can reduce such issues. If you can’t handle it yourself, get it checked by a professional shop early to avoid damaging the catalytic converter.
