P0117

DTC P0117 or P0118

DTC Descriptors
DTC P0117
- Engine Coolant Temperature (ECT) Sensor Circuit Low Voltage

DTC P0118
- Engine Coolant Temperature (ECT) Sensor Circuit High Voltage

Diagnostic Fault Information

Perform the Diagnostic System Check - Vehicle Diagnostic System Check - Vehicle prior to using this diagnostic procedure.






Typical Scan Tool Data






Circuit Description

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:






Conditions for Running the DTC

P0117
* The engine is running for more than 2 minutes.
* The ignition has been off for more than 10 minutes before the vehicle is started.
* This DTC runs continuously when the above condition is met.

P0118
* The engine is running for more than 2 minutes.
* The intake air temperature (IAT) sensor is greater than 15°C (59°F).
* This DTC runs continuously when the above condition is met.

Conditions for Setting the DTC

P0117

The ECM detects that the ECT sensor is more than 149°C (300°F).

P0118

The ECM detects that the ECT sensor is less than -38°C (-34°F).

Action Taken When the DTC Sets

DTC P0117 and P0118 are Type B DTCs.

Conditions for Clearing the MIL/DTC

DTC P0117 and P0118 are Type B DTCs.

Diagnostic Aids

* After starting the engine, the ECT sensor temperature should rise steadily, then stabilize after the thermostat opens.
* 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 driveability condition.
* If the vehicle has set overnight, the ECT sensor and the IAT sensor values should display within 3°C (5°F).

Reference Information

Schematic Reference

Engine Controls Schematics Electrical Diagrams

Connector End View Reference
* Engine Control Module (ECM) Connector End Views Engine Control Module (ECM) Connector End Views
* Engine Controls Connector End Views Engine Controls Connector End Views

Electrical Information Reference
* Circuit Testing Circuit Testing
* Connector Repairs Connector Repairs
* Testing for Intermittent Conditions and Poor Connections Testing for Intermittent Conditions and Poor Connections
* Wiring Repairs Wiring Repairs

DTC Type Reference

Diagnostic Trouble Code (DTC) Type Definitions Diagnostic Trouble Code (DTC) Type Definitions

Scan Tool Reference
* Scan Tool Data List Scan Tool Data List
* Scan Tool Data Definitions Scan Tool Data Definitions
* Scan Tool Output Controls Scan Tool Output Controls

Circuit/System Verification

1. Engine running, DTC P0117 and P0118 should not set.
2. If the vehicle passes the Circuit/System Verification Test, then operate the vehicle within the conditions for running the DTC. You may also operate the vehicle within the conditions that are captured in the Freeze Frame/Failure Records Data List.

Circuit/System Testing

1. Ignition OFF, disconnect the harness connector at the ECT sensor.
2. Ignition OFF, test for less than 5 ohms of resistance between the low reference circuit and ground.

• If greater than 5 ohms, test the low reference circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the ECM.

3. Ignition ON, using a scan tool verify that the ECT sensor parameter is at -40°C (-40°F).

• If greater than -40°C (-40°F), test the signal circuit of the ECT sensor for a short to ground. If the circuit tests normal, replace the ECM.

Important: If the signal circuit of the ECT sensor is shorted to voltage, the ECT sensor may be damaged.


4. Install a 3-amp fused jumper wire between the signal circuit and the low reference circuit. Verify the ECT sensor parameter is greater than 128°C (262°F).

• If less than 128°C (262°F), test the signal circuit of the ECT sensor for a short to voltage or an open/high resistance. If the circuit test normal, replace the ECM.

5. If all circuits test normal, test or replace the ECT sensor.

Component Testing

1. Ignition OFF, disconnect the harness connector of the ECT sensor.

Important: A thermometer can be used to the used to test the sensor off the vehicle.


2. Test the ECT sensor by varying the sensor temperature while monitoring the sensor resistance. Compare the readings with the Temperature vs Resistance Temperature vs Resistance table and verify that the resistance is within 5 percent of the specification.

• If the resistance vs temperature is not within 5 percent, replace the ECT sensor.

Repair Instructions

Important: Always perform the Diagnostic Repair Verification Diagnostic Repair Verification after completing the diagnostic procedure.


* Engine Coolant Temperature (ECT) Sensor Replacement Service and Repair
* Control Module References Control Module References for engine control module replacement, setup, and programming