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.
Trip Indicator
The trip is essential for running monitors and turning off the Malfunction Indicator Light (MIL). A trip is defined as a set of vehicle operating conditions that must be met for a specific monitor to run. All trips begin with an ignition key cycle. Good trip counters are global good trip, fuel system good trip and misfire good trip.
- Global Good Trip
To count as a good trip, oxygen sensor monitor and catalyst efficiency monitor must run and pass. - Fuel System Good Trip
To count as a good trip (3 required) and turn off the MIL, the following conditions must be met. Engine must be in closed loop, must be operating in similar conditions window and short term multiplied by long term must be less than threshold value. - Misfire Good Trip
If operating in similar conditions window and 1000 engine revolutions have occurred with no misfires, the PCM will count one good trip (3 required) in order to turn off MIL. - Warm-Up Cycles
Once the MIL has been turned off by the good trip counter, the PCM will automatically switch to a warm-up cycle counter that can be viewed by the DRBIII® scan tool. Warm-up cycles are used to clear DTCs and freeze frame data from PCM memory. Forty warm-up cycles (80 for fuel system monitor or misfire monitor) are necessary to clear DTCS and freeze frame data. A warm-up cycle is defined as the engine is started, an increase of 40°F (4°C) in engine coolant temperature exists after engine is started and engine coolant temperature reaches at least 160°F (71°C).
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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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