Are all ECU's made equal?

I recently had the dealership diagnose my car starting problem as a bad ECU. Since its easy enough to replace I ordered a used (but tested) ECU from a salvage yard. Only catch is, my car is a 1996 Honda Accord DX, and when the ECU arrived, I realized the part number was swapped out for the LX model of the same year. The seller tried to alleviate my concerns by saying that they are interchangeable, and I want to believe him because the car starts like a charm now. However, now I have a check engine light for P0441 which wasn’t there with the old ECU. Since the car starts and seemingly runs just fine, should I trust this ECU and start chasing the Evap code?

I really don’t think a sympton of an incompatible ECU would be to run but set an evap code. I am not dealing with first hand experience with this issue but just adding things up.

Problem is that many states now need a clean read of the ECU to pass your car inspection. The LX DX issue may not be what you need to focus on. The evap system may have an issue. It may be fixed but it will be an expert on these models to answer you.

How about clearing the codes one more time to see if it comes back?

ECUs can vary during the same year model so I’d say that it’s at least possible they may not interchange fully.

You could go to the AutoZone website under Repair Info and look over some of the Engine Control Wiring schematics for this year. Compare the various pins and wire codes to make sure they all match along with any notes about any Federal or California differences.

I did try clearing it, tightenig the gas cap, and the same code it popped up again after going above 45mph. Question is, since this code wasn’t there with the other ecu, can I trust this code?

You hit the nail on the head, I live in Ca and have only 5 days to pass smog with this code!

Clear the code.
Drive like a snail to inspection.
Pass inspection.

Then work on repairing the code.

You may be seeing one of the reasons the first ECU went bad the first time.
WHY was the first one bad ? ( Kinda like a fuse. they dont just ‘wear out’. There’s a reason the first one went bad.)
I hope you’re not on the way to ruining this second one.

Yeah, I tried that. Couldn’t pass because they said obd11 hadn’t gone through all it’s self diagnostic and I’d have to drive it around more and retest. But you raise an excellent point about why the first ecu went bad ( or at least wasn’t giving a ground to the main relay). Any ideas?

I had an evap leak issue on my 2002 Sienna. Very intermittent, turned out to be something in the canister assembly.

but, I learned the leak test is done only under very specific conditions, and it took time from my house, like 10 minutes, before it would fail – when it failed.

So, the 45 mph may be related to time from your house, not speed. If you think it over, you can tell if that is the case.