I need to replace the engine control unit, ECU, of my Honda Civic 2000, my car doesn't have an immobilizer, it starts with a basic metal key, so, do I need to program the used ECU replacement?

  • If it starts, why do you think you need to replace the ecu?
    – Solar Mike
    May 13, 2019 at 4:33
  • When it turned on before the ECU was damaged.
    – Alan
    May 13, 2019 at 4:52
  • Any chance of damaging something if it start without programming and use it like that? Does the ECU needs to be installed for programming?
    – Alan
    May 13, 2019 at 5:22
  • Yes & Yes, so take it to someone who can. I assume you don't have a fully capable programmer.
    – Solar Mike
    May 13, 2019 at 5:23

2 Answers 2


As it is clear that the old ecu is damaged then if it does not start with the new ecu, then it definitely needs programming.

If it does start, then it may need programming for best performance etc


Unless its actually a 1999 then it should be equipped with a immobilizer. 2000+ Honda Civics all use transponders so if its actually a 2000 and one is starting with an all metal key then 1 of 2 things have happened.

  1. The ecu was modified and the immobilizer was tuned out or emulated inside the ecu.
  2. Someone has taped a key or transponder under the dash inside the antenna.

A proper ecu replacement will need to have the immobilizer tuned out again or either the ecu will need matching with the immobilizer system AND key with properly coded transponder inside. I usually prefer HDS (honda diagnostics software) or Autel's 908 but many tools can do these older Honda immo systems.

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