So I have an 04 EP3. The ECU got stolen and I replaced it with an ECU from a base model RSX. It's part number is 37820-pnd-a09. It works and all but the CEL is on. I haven't pulled any codes yet but I was wondering what can possibly turn on the CEL. The CEL was not on with the actual EP3 ECU. **** out of luck and just get the right ECU?

 

it may have to be rekeyed? is your immobilizer plugged in?

 

i took it to honda and had them rekey it. Everything works just fine. The car runs smooth etc. I thought the immobilizer was built into the ECU. It's seperate?

 

yeah it is seperate, except i cannot tell you where it is due to HT forum rules....check over at clubep3, see if they can tell you

 

But if it wasn't plugged in, then the car wouldnt start right?

 

You should check what codes it's throwing before you speculate. You could be completely off and just worrying yourself for nothing when it's a possibility that it could just be a misfire or something normal.

 

^^Yeah. But the ECU I stated should work without throwing codes even though it's not meant for the car right? Can anyone comment on that?

 

It could be because they have different intake manifolds. I'm not sure if that would affect anything but, maybe it's throwing off the A/F mix thus causing a code.... hence the recommendation of checking the codes before jumping to conclusions.