I just bought a 2000 SSEi w 170,000. Recentky the car vibrates in idel and when i start to accellerate, the car misfires. When i hooked up obd2 i got a code p0300 and p0420. Multiple cylinder misfires and pre cat o2 sensor. I replaced plugs and wires now i discovered one of the coil packs is bad. I plan on replacing all 3 but im curious, how do i know if the icm not working properly? When i remove the coils is there a way to test the ignition control module? I hope this will resolve my issues with vibration and misfires and send the right signal to the o2 sensor. Any other thoughts? Thanks.

If you have one bad coil pack, replace or move it to another location on the ICM and see if the coil pack failure follows the coil, if so its the coil. If its always missing on the same location regardless what coil pack is on there then its the ICM.

As for the P0420 I would fix your ignition issue and clear codes and see if it comes back.. if its running bad that could cause a bad reading for the Cat efficiency. if it comes back the cat isn't doing its job and may needs replaced. I would suggest a ZZP Downpipe with a magnaflow cat to replace it, runs better and better MPG.

S

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Shane "RedZMonte"
2004 Z16 Z06: Virgin
2000 SSEi: Kenwood DDX512, 3.25" MPS, ZZP DP, PLog, Puck Mount, NGK TR7's, DHP Tuned
1995 Monte Z34: T04e "60" turbo, 42.5# injectors, Borla Catback, OBDII swap, DHP Tuned, Much more...

Thank you Shane. I will test the icm as per your suggestion. Im anxious to get the misfire issue cleared up. I appreciate your advise.