• | Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. |
• | Review Strategy Based Diagnosis or an overview of the diagnostic approach. |
• | Diagnostic Procedure Instructions provides an overview of each diagnostic category. |
Circuit | Short to Ground | High Resistance | Open | Short to Voltage | Signal Performance |
---|---|---|---|---|---|
ECT Sensor Signal | P0117 | P0118 | P0118 | P0118 | P0116, P0125, P0128 |
Low Reference | -- | P0118 | P0118 | P0118, P0651 | P0125, P0128 |
Circuit | Short to Ground | Open | Short to Voltage |
---|---|---|---|
Parameter Normal Range: -39 to +120°C (-38 to +248°F) | |||
ECT Sensor Signal | 150°C (302°F) | -40°C (-40°F) | -40°C (-40°F) |
Low Reference | -- | -40°C (-40°F) | -40°C (-40°F) |
The engine coolant temperature (ECT) sensor is a variable resistor that measures the temperature of the engine coolant. The engine control module (ECM) supplies 5 volts to the ECT sensor signal circuit and supplies a ground to the low reference circuit.
• | The engine is running for more than 10 seconds. |
OR |
• | The engine run time is less than 10 seconds when the intake air temperature (IAT) is colder than 50°C (122°F). |
• | This DTC runs continuously within the enabling conditions. |
• | The engine is running for more than 10 seconds. |
OR |
• | The IAT is more warmer 0°C (32°F). |
• | This DTC runs continuously within the enabling conditions. |
The ECM detects that the ECT is warmer than 149°C (300°F) for more than 5 seconds.
The ECM detects that the ECT is colder than -39°C (-38°F) for more than 5 seconds.
DTCs P0117 and P0118 are Type B DTCs.
DTCs P0117 and P0118 are Type B DTCs.
• | If an engine overheating condition exists, it is possible to set a DTC P0117. Verify the proper heat range and the operation of the thermostat. Refer to Thermostat Diagnosis. |
• | An ECT sensor signal circuit or low reference circuit that is shorted to another 5-volt reference circuit can cause a DTC P0118 to set. |
Powertrain Diagnostic Trouble Code (DTC) Type Definitions
Control Module References for scan tool information
⇒ | If greater than the specified range, test the low reference circuit for an open/high resistance. If the circuit tests normal, replace the ECM. |
⇒ | If greater than the specified range, test the signal circuit terminal A for a short to ground. If the circuit tests normal, replace the ECM. |
⇒ | If less than the specified range, test the signal circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the ECM. |
Measure and record the resistance of the ECT sensor at various ambient temperatures, then compare those measurements to the Temperature vs Resistance table. Refer to Temperature Versus Resistance.
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
• | Control Module References for ECM replacement, setup, and programming |