Powertrain Control Module (PCM) monitors several different engine control system circuits. If a malfunction occurs, PCM will record a Diagnostic Trouble Code (DTC) the next time engine is started and the same malfunction is detected.

PCM will erase a DTC when malfunction is not detected during 40 run/stop cycles of engine. PCM will erase a DTC for a misfire or fuel trim malfunction when no malfunction is detected for 80 run/stop cycles of engine with engine speed, coolant temperature, or other parameters similar to when malfunction first occurred.

When a DTC is stored, PCM will also record and store engine operating conditions when malfunction occurred. This information is referred to as freeze frame data. Freeze frame data will be stored in PCM memory until cleared, with the exception of the occurrence of an engine misfire or fuel trim malfunction. When a misfire of fuel trim fault occurs, freeze frame data will be updated with the most current information regarding these failures.

Freeze frame data recorded is:

Engine coolant temperature.
Engine speed.
Vehicle speed.
Long term fuel compensation (long term fuel trim - displayed as percent).
Short term fuel compensation (short term fuel trim - displayed as percent).
Fuel control condition: Open or closed loop. Malfunction of rear O2S.
Calculated load value (displayed as percent).
Diagnostic Trouble Code (DTC) during data recording.

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.

Safety Warning

On-Board Diagnostics

Use the Manual With the Right Hardware

When to See a Mechanic