It will work.
Well, I installed the ECU and used security access to add it. That worked fine. Car started okay.Only $20! Nice grab.
I noticed the Check Engine light was on, and erased it. Check Engine light never reappeared.
Nevertheless, car drove oddly, with a lot of surging when accelerating, with the turbo gauge bouncing around.
My old-time ODB II reader reports:
(This, despite the fact that Check Engine isn't on.)
Car is not driveable on the highway, it's very slow and smells bad.
Is this an ECU fault, or do I have to do SPS programming? As I said, part number is 55565020 out of a facelifted 9-3. It's been put in a 2004 Aero. Obviously it is not usable as is.
Note 1: the only other thing I did was pull the air filter to inspect. This meant unplugging and replugging the sensor in the filter box outlet pipe.
Note 2: Who designed the connectors to the ECU? They were frozen solid. I had to do prying with a screwdriver to get them loose, and the metal bail clip on the RH connector popped loose and won't go properly back in place (I sort of squeezed it back on). The connector was very reluctant to slide in and out even when the ECU wasn't there. I moved it back and forth and cleaned up crud but both are still cruddy and stick at each end. Just releasing the metal clip and pulling up on it, or trying to attach the connector by moving the metal clip forward and down, is much more likely to unseat the clip than to move anything. Ugh.