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.
Reading Service Codes
Engine control system communicates malfunctions to technician through service codes. These service codes are 2-digit numbers representing a particular defect. Service codes are transmitted through STO connector.
Service codes are displayed as timed pulses, and may be read with a VOM, NGS, or Super Star II tester. VOM displays codes by needle sweeps. See Fig 1 .
Turn ignition off. Follow all procedures of EQUIPMENT HOOK-UP. Engine should be at normal operating temperature.
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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.