Diagnostic Aids

For any test that requires probing ECM or component harness connectors, use Connector Test Adapter Kit (J-35616-A). This will prevent damage to harness connector terminals. Check for the following conditions:

Check for poor connections at ECM or at component. Inspect harness connectors for backed out terminals, improper mating, broken locks, improperly formed or damaged terminals and poor terminal-to-wire connection.

Check for damaged wiring harness. If harness appears to be okay, observe scan tool while moving related connectors and wiring harnesses. A change in scan tool display may help to locate fault. If sensor signal is only affected when harness is moved at a component, and there is no problem with wiring harness or connections, component may be faulty.

If other DTCs are set that share the same ground circuit, check point where circuits ground to chassis or engine block. If engine has been allowed to sit overnight, ECT and IAT values should be within a few degrees of each other. If temperatures are not within 5°F (3°C), refer to ECT TEMPERATURE VS. RESISTANCE  table under DTC P0115.

When checking ECT sensor, refer to ECT TEMPERATURE VS. RESISTANCE  table under DTC P0115 to test sensor at various temperature levels and to check for shifted sensor. A shifted sensor could result in poor driveability complaints.

Check for stuck open thermostat. A stuck thermostat during very cold temperatures will cause engine temperature to increase too slowly and could result in this DTC being set.