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.
Permanent DTC
In accordance with SAE J1979, TCM stores DTCs that adversely affect vehicle emission (i.e. DTCs with MIL turning on) in a non-volatile RAM (NVRAM) separately from that for pending and confirmed DTCs. This DTC is called a permanent DTC.
Unlike pending and confirmed DTCs, the permanent DTC will not be cleared even when executing the clear command of scan tool or when shutting off the power to TCM. Only when does TCM detect no malfunction in the trouble area of the stored permanent DTC with the condition determined normal the permanent DTC will be cleared. (For permanent DTC clearance, refer to DTC CLEARANCE )
The maximum of four earliest detections of the permanent DTCs will be stored in memory. The DTCs are cleared in the order of completing determination as normal.
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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.