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.
Check For Intermittent Problems
HINT:
Intelligent tester only:
Inspect the vehicle's ECM using check mode. Intermittent problems are easier to detect with an intelligent tester when the ECM is in check mode. In check mode, the ECM uses 1 trip detection logic, which is more sensitive to malfunctions than normal mode (default), which uses 2 trip detection logic.
- Clear the DTCs (See DTC CHECK / CLEAR ).
- Switch the ECM from normal mode to check mode using an intelligent tester (See CHECK MODE PROCEDURE ).
- Perform a simulation test (See HOW TO TROUBLESHOOT ECU CONTROLLED SYSTEMS ).
- Check and wiggle the harnesses, connectors and terminals (See ELECTRONIC CIRCUIT INSPECTION PROCEDURE ).
Use the Manual With the Right Hardware
Pair factory procedures with proven DIY tools so the instructions are easier to execute.
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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.