I have a 2000 Saturn SL with manual tranny that started reporting EGR valve issue P1404. I traced fault to missing 12V at EGR valve from PCM. Wiring between PCM and EGR OK, no opens or ground faults. I ordered a salvage-yard PCM of exact same part number and type as original unit; it arrived and looks identical to existing faulty PCM, same part number. I did this because I assumed it would be plug-and-play, no need for dealer to program car VIN number into replacement PCM. I installed it and observed 12V to EGR valve now present; primary problem solved. But new problem #2 is now car won't start, it cranks but will not start. Also fuel gauge doesn't move off 'E' even though tank has 1/2 tank of gas. I reinstalled 'faulty' PCM and engine starts fine and fuel gauge reads 1/2 of gas. I contacted salvage yard and they say I need to take PCM to dealer and have them program in car VIN, allegedly because PCM is unable to communicate with other car components such as IP cluster. This sounds contrary to what little I've read about this type of PCM. I had understood that VIN didn't matter. It would mean other items like Instrument Panel cluster, if replaced, also require reprogramming with VIN. If replacement PCM requires reprogramming with existing VIN then what is PCM communicating with that is checking for legacy VIN? BTW, this car is no frills, manual transmission, no security, manual windows, no key fobs, probably most basic, least expensive car they produced.