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 Infiniti M30FACTORY OEM SERVICE PROCEDURE
Entering Self-Diagnostics
- Turn ignition on, but leave engine off. Using a small screwdriver, turn diagnostic mode selector on ECU fully clockwise. Wait at least 2 seconds and then turn diagnostic mode selector fully counterclockwise. Mode II self-diagnostic will result and the CHECK ENGINE light and the Red LED inspection light will flash trouble codes (if present).
- If engine is started at this stage, the CHECK ENGINE light and the Red LED inspection light will display the condition of the air/fuel mixture which is monitored by the O2 sensor or if the system is in closed or open loop.
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.