I have a 2006 XC90 AWD engine D5244T4. I am trying to resolve the error code P0204. I understand this to be either injector failure, the wiring between the injector and the ECU or the ECU itself. Not having a scope, I've checked the resistance of injector 4 and injector 5 and the continuity between the relevant ECU pins and the injector. These all checked out to be OK - injector 4 and 5 resistance identical and there were no breaks between the injector and ECU. I hope I am correct in assuming the problem lies within the ECU ??. I have an opportunity to buy an ECU that was fitted to an identical model, the only difference being model year 2007 and not 2006. Will this be compatible for my car?

 

ECU's and a lot of other modules are specific to the car (via the VIN) and cannot be swapped out. Have you tried swapping the injector location to another cylinder. clearing the codes, and seeing if the code moves with the injector? ie P0204 turns into P0205.

 

Thanks for this Dingus1. I'll try the swap.

 

also inspect the wiring - look for corrosion or cracks by the injector. You may also try reseating the ECU (cleaning the contacts with electronic cleaner is also worth a try)

 

Thanks for this. I think the wiring between the injector and the ECU is OK. I think this because I get almost identical resistance readings when I measure directly across injector 4 and when I measure between the corresponding female connections on the plug that connects to the ECU. I would expect a significant difference if there were corrosion or breakages at the injector. I'll do the reseating and cleaning.