2001 Honda Accord P0300 P0304 P0305 P0306 C1555 - Cylinder Misfire and Rough Idle Diagnosis
I have a 2001 Honda Accord that started showing issues two days ago. While driving on the highway, I noticed the check engine light came on and began flashing, accompanied by noticeable engine vibration. The car ran roughly with an irregular idle. The next morning, I scanned the system at AutoZone and found the following diagnostic codes: P0300 (random/multiple cylinder misfire), P0304 (cylinder 4 misfire), P0305 (cylinder 5 misfire), P0306 (cylinder 6 misfire), and C1555 (cylinder 4, 5, 6 misfire detected). I already replaced the spark plugs and swapped the coil pack from cylinder 2 to cylinder 4, but there was no improvement. The engine continues to run roughly and the codes persist. Has anyone else experienced this issue with a 2001 Honda Accord? If so, any advice or troubleshooting steps would be greatly appreciated.
Hello, I've seen this issue on my 2001 Honda Accord. It's often related to engine piston problems. The vehicle may have a technical service bulletin (TSB) recommending spark plug replacement and an oil change. However, in most cases, the underlying issue requires full engine disassembly to inspect and repair the pistons. I recommend taking it to a dealership for diagnosis—some models from this era are covered under warranty for such issues. Thanks!