P0403 code in a Subaru engine swap

I have 2 Subarus and I did an engine swap. Here are the details:

Car 1: 1996 Subaru Legacy L (the engine from this car has an EGR valve)

Car 2: 1997 Subaru Brighton (This engine did NOT have an EGR valve)

So.... I put the engine from car 2 into car 1. I figured that as long as I put the ECU from car 2 into car one, the only difference would be that there is an unused wire from ECU that would have gone to the EGR solenoid.

So I have both the engine and ECU from car 2 into car 1 now. The engine harness is from car 2, so it is the right harness for the engine. The body harness that goes to the ECU is the original one from car 1.

The OBD is giving me a p0403 and p0403p/d. This car does not even have an EGR system and it doesn't have an EGR solenoid valve, either.

I am stumped as to what I can do to make the light go off. I have tried disconnecting the battery for a period of time, and it doesn't go off. It is not left over from the original ECU, either, because the light went off after I put the new ECU in and then after the second time I started it, it went on again with the same code.

I called a subaru dealer and they said that maybe I could put a diode in place of where the solenoid might be. I was also thinking just jumping where the circuit would be, but I would put a fuse in to make sure I don't fry anything.

Also, could I just splice in the whole solenoid into the circuit where it would have been just so that the ECU sees that there is something in the circuit?

It just doesn't make sense that an ECU that never had an EGR solenoid is now telling me that there is a circuit malfunction to it.

Thanks for any help. I have a guy with money in his hand who wants to buy it as soon as the light goes out.

I dont know for sure. You might have to change out the body harness too. There could be a power wire which enables the EGR circuit. Can you compare the two harness's at the ECU plug ?
Good luck,
Aeroman.

Both harnesses have the same wires going to the ECU.

Today, I hooked up the EGR solenoid to the correct terminals at the main relay and the ECU, and the check engine light was off. I unplugged the EGR solenoid and after a couple minutes, the light came on. Then I disconnected the battery and started something else. I have not checked it again.

I sure hope the code goes away with it hooked up the second time I start it up again.

too me it makes sense! if the harness from the engine that had the egr is being used with an engine and ecu that doesn't and the ecu's plug in place of each other then it's not suprising because the egr line is open circuit! it's likely being commanded on even by the ecu but you'd need a scan tool to try an actuator test! if the ecu from the engine without the egr can be used then it would be a quick check!

I have tried both ECUs. They both give the EGR code.

Ypu might have to get the computer reflashed from the dealer, unless you have a hand held tuner you can borrow.

Aeroman.

yeah but without a working egr it's going to generate an egr code! If the command is there it need to see it actuatr and the 02 switch as a result!

Jeff, I understand that completely. WHat I don't understand is that the ECU that is in the car came from the engine without and EGR system! I just don't understand what is different between the two vehicles that would make BOTH ECUs give me an EGR circuit code. Why didn't this ECU give me an EGR code when it was in the original car with the original engine?

I read that the ECU is just looking for the load because it is just a solenoid. How come it needs to see a load in this car but it didn't need to see it in the other car?

I'd have to look at the wiring diagram and see! It can be as simple as another module in the car still thinks it's the old engine and the ecu then thinks that it's the old engine because it's being told it is!! Know what i mean, kinda like a neighbour down the street that doesn't know you've moved out and keeps calling your old phone number. A Mr Smith Has moved out and a Mr brown has moved in but Mr Johnson 2 blocks away is still calling the new tenants Mr Smith. That's kinda how BUS systems in vehicles work and I know it's a weird analogy but that maybe what's happening.

Yeah, I understand. I will try to scan and post my wiring diagram from my haynes manual. It basically shows this: All components are in parallel from the main relay which has a switchable hot side to the ECU. That is pretty much it. The EGR solenoid is just in parallel with the rest of the components like the Fuel Purge valve, the 2 O2 sensors and a few other components.

This is why I am still skepticle about any changes in the wiring harness. I know it must be different somewhere, I am probably just in denial.

Thanks for everyones help, it is nice to throw ideas around.

Do you still have the ECU for the 96 Legacy? I need a replacement. The code as seen on my unit is: T9 22611 AB630 A18-000 RV3. Pls advise

This ever get fixed? Sounds like you might be able to get away with a resistor of the same value as the EGR solenoid...

YEah. Well, kinda. I just spliced in the solenoid. I mounted it on to one of the bolts under the kick plate that goes over the ECU. The guy I sold it to hasn't had any problems with it for over 1000 miles so far.