I live in a very rural town in Louisiana and any knowledge with Honda ECU issues is non existent here and I want to thank this entire forum for past help with this car. My son has an 01' Civic LX 1.7 auto that was given to us by my brother with the alternator/fried ECU/Limp mode issue. Fixed alternator issue and I bought what is supposed to be matching used ECU and entire complete ignition key cylinder. Car spins over but will not start. Green Key Symbol flashes repeatedly. Should this have been a simple parts swap and go or is there a step I missed? Thank you for any and all help.

 

I had similar issues with the immobilizer. I swapped the ECU and the transponders in the key but still got the green flashing key. Heard in a few places that the ECU will sometimes forget keys? Not sure if that's the case or if bad ground fried my replacement ECU 🤣. Either way I unsoldered the immobilizer chip and it started again. Key blinks but it runs. Tried the stealerships first for programming but they acted like they didn't know wtf I was asking for. On top of that neither brake code was working.

 

Thanks for the reply. The chip you're referring to is the 8 pin chip on ECU PCB I assume? Does your car run ok with key flashing or is it in Limp mode? I have 1 Honda dealer and it's 70 miles from me. 2nd is 180 miles. I called and they acted like me asking them to program new ECU and keys was just the most exotic thing they'd ever heard. Told me to bring car and leave it. Said even if they couldn't do anything if still owe them $400. They're crazy.

 

You need the keys, the receiver ring for the ignition, the ecu and the micu all to match.