• | Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. |
• | Review Strategy Based Diagnosis for an overview of the diagnostic approach. |
• | Diagnostic Procedure Instructions provides an overview of each diagnostic category. |
Circuit | Short to Ground | Open/High Resistance | Short to Voltage | Signal Performance |
---|---|---|---|---|
ECT Sensor Signal | P0117 | P0118, P0119 | P0118, P0119* | P0116 |
Low Reference | -- | P0118, P0119 | P0118, P0119* | P0116 |
* Sensor or ECM damage may occur if the circuit is shorted to B+ |
Circuit | Short to Ground | Open | Short to Voltage |
---|---|---|---|
Operating Conditions: Engine operating in Closed Loop. Parameter Normal Range: -39 to 142°C (-38 to 288°F) Varies with coolant temperature. | |||
ECT Sensor Signal | 143°C (289°F) | -40°C (-40°F) | -40°C (-40°F)* |
Low Reference | -- | -40°C (-40°F) | -40°C (-40°F)* |
* Internal ECM or ECT sensor damage may occur if the circuit is shorted to B+ |
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 signal circuit and supplies a ground to the low reference circuit.
The following table illustrates the difference between temperature, resistance, and voltage:
ECT | ECT Resistance | ECT Signal Voltage |
---|---|---|
Cold | High | High |
Warm | Low | Low |
• | The engine is operating. |
• | The start up intake air temperature (IAT) is colder than 72°C (161°F). |
OR
• | The start up intake air temperature (IAT) is warmer than 72°C (161°F). |
• | The engine run time is greater than 59 seconds. |
• | The DTC runs continuously once the above conditions are met. |
• | The ignition is ON or the engine is operating. |
• | The DTC runs continuously once the above condition is met. |
The ECM detects that the ECT is warmer than 140°C (284°F) for greater than 4 seconds or a cumulative of 30 seconds.
The ECM detects that the ECT is colder than -39°C (-38°F) for greater than 4 seconds or a cumulative of 30 seconds.
DTC P0117 and P0118 are Type B DTCs.
DTC P0117 and P0118 are Type B DTCs.
• | Test the ECT sensor at various temperature levels in order to evaluate the possibility of a skewed sensor. A skewed sensor can result in a DTC or a driveability condition. Refer to Temperature Versus Resistance - Engine Coolant Temperature Sensor. |
• | If the vehicle has sat overnight, the scan tool IAT sensor and ECT sensor parameters should display within 3°C (5°F) of each other. |
• | After starting a cold engine, the ECT sensor temperature should rise steadily, then stabilize after the thermostat opens. |
• | High resistance in the circuits of either the ECT or IAT sensor could set a DTC. |
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. |
Caution: Do NOT use a test lamp to test the continuity of the circuit. Damage to the control module may occur due to excessive current draw.
Note: The control module or the sensor may be damaged if the circuit is shorted to B+.
⇒ | If greater than the specified value, test the low reference circuit for a short to B+. If the circuit tests normal, replace the ECM. |
⇒ | If warmer than the specified value, test the signal circuit for a short to ground. If the circuit tests normal, replace the ECM. |
Note: If the fuse in the jumper wire opens, the signal circuit is shorted to a voltage and the sensor may be damaged.
⇒ | If colder than the specified value, test the signal circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the ECM. |
Note: A thermometer can be used to test the sensor off the vehicle.
⇒ | If not within the specified value, replace the ECT sensor. |
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
• | Control Module References for engine control module replacement, setup, and programming |