Question about H22 EK hatch, CEL related, P28 ECU

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I just bought a '98 EK hatch with a JDM H22A under the hood. When I picked the car up, the owner had the OBDII H22 ECU running the car (can't remember the code at the moment) which threw a CEL on the 2 hour drive home due to the unplugged EGR sensor as well as the lack of a 2nd O2 sensor in the cat. So, in short, we expected the CEL.

Today, I got the OBDII - OBDI conversion harness so I could swap back to the H22 programmed P28 ECU that the owner gave me with the car. The problem is, the car runs with that ECU and it runs OK, but the CEL is still on. So, like any good hondaboy I pulled the EFI fuse, waited, and turned the car back on - the CEL came back? So, I shorted the service connector in the passenger side kick panel, turned the key to ignition, and the CEL stays solid - no blinking codes. Anyone have any ideas what this thing might be trying to tell me? The P28 runs the car fine, but it feels week in VTEC - I would liken it to clutch slip but I know that's not it, it just seems like something is holding it back... a lot. I'm gonna head to the dyno next week anyway to run both the P28 and the OBDII H22 ECU to see if I can't get a handle on what's going on, but I'd like to get this CEL issue fixed or at least some light shed on it.

Answers are much appreciated!

Oh yea, the car is a JDM H22A with 290cc injectors, there is no resistor box and from my searching, it would appear that I don't need one for these injectors anyway.

Thanks again, Todd.


Staff member
1992-96 Prelude non-vtec Peak and hold 240cc
1992-96 Prelude VTEC Peak and hold 345cc
1997-up Prelude VTEC Saturated 280cc

assuming your motor is 97 or newer, you should be ok with the saturated ones and no resistor box.

usually when the cel is sold and doesn't turn off, its a probalem with the ecu--- or, more likely, the conversion harness is wrong, or the chip burt onto the p28 is bunk, or not seated properly in the socket.