Test Description

Number(s) below refer to the step number(s) on the Diagnostic Table.

1. The On-Board Diagnostic (OBD II) System Check prompts the technician to complete some basic checks and store the Freeze Frame and Failure Records data on the scan tool if applicable. This creates an electronic copy of the data taken when the malfunction occurred. The information is then stored on the scan tool for later reference.
2. The engine must be allowed to cool fully before the ECT and IAT sensors will read close to the ambient temperature in order to check for a possible skewed sensor.
3. To test the thermostat, refer to the THERMOSTAT TEST .
4. Measure the engine coolant temperature with a thermometer to determine the actual value the ECT This sensor should be. Take into consideration if the engine coolant has been run and the engine coolant has been warmed without opening the thermostat.
5. This step simulates a DTC P0118. If the ECM senses the change, the ECM and wiring are OK.
6. The replacement ECM must be reprogrammed.

   Refer to the latest Techline procedure for ECM programming.