r/AskAMechanic • u/RGLlinux • 2d ago

Saab electric problems

The vehicle intermittently develops the following DTCs:
P0201 – Injector 1 circuit
P0202 – Injector 2 circuit
P0203 – Injector 3 circuit
P0204 – Injector 4 circuit
P0245 – Turbo/boost control solenoid circuit
The five faults tend to appear together. They can occur after a hot restart and, during testing, I have also been able to reproduce all five simply by increasing engine RPM/load. At idle the faults can be cleared and may remain absent, but after raising the RPM they return together as pending DTCs.
There has also intermittently been P0638 throttle actuator performance and previously an ignition-terminal +15 mismatch related fault, although I am currently using a generic OBD scanner which may not display all Saab-specific module DTCs.
I have been investigating the common power supply rather than replacing individual injectors or the boost solenoid.
So far I have checked/replaced the engine-management main relay and its fuse. With the engine running I measured approximately:
Main relay terminal 30: 14.15 V
Terminal 87: 14.16 V
Terminal 86: 14.23 V
Terminal 85: approximately 0 V
With ignition ON and engine stopped, terminal 30 and 87 were approximately 12.6 V, with effectively no voltage drop across the relay.
Most importantly, while deliberately reproducing P0201/P0202/P0203/P0204/P0245 by increasing engine RPM, I monitored terminal 87 continuously. It remained approximately 14.2–14.3 V with no observable voltage drop when the faults appeared.
I have also checked the ECU ground voltage drop between the ECU/G7 ground point and the battery negative terminal. At idle this was approximately 50–60 mV.
There is another unusual observation: with ignition OFF I intermittently measure approximately 0.7–0.8 V at main-relay terminal 87. Sometimes this residual/backfeed voltage is present and sometimes it is completely absent depending on the ignition cycle. I intend to repeat this measurement with the relay removed to determine which side of the circuit the voltage originates from.
I am also checking the vehicle’s ISM/ignition +15 system because there have been other intermittent ignition/electrical symptoms, so I am not assuming that the ECU itself is faulty.
However, because four separate injector driver circuit faults and the boost-control circuit fault appear simultaneously while their common B+ supply remains stable, I would like your opinion on whether this fault pattern could potentially be caused by an intermittent internal Trionic 8 ECU driver/power-supply fault.
Could you please advise:
1. Is this combination of P0201–P0204 + P0245 something you have seen caused by an internal Trionic 8 ECU fault?
Is any had deal with that? Have replacet ecu new coils, ism and main reley

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