Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
1990 Saab 9000 CD, AutomaticFACTORY OEM SERVICE PROCEDURE
Error Code 12231
- The check engine light is off. There is no RPM signal. This code will always be present if the test is run with the engine off. Crank engine for 5 seconds. If code disappears, the RPM signal is OK. If code does not disappear, go to step 2.
- Check fuse no. 3. Check the ignition system input at pin 1 of the LH control unit.
Factory Service Tools
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.
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