P0118

DTC P0117 or P0118

Diagnostic Instructions

* Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. Initial Inspection and Diagnostic Overview
* Review Strategy Based Diagnosis for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions provide an overview of each diagnostic category.

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






Typical Scan Tool Data






Circuit/System 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.

Conditions for Running the DTC

P0117
* The engine is running for greater than 10 seconds.
OR
* The ignition is ON when the intake air temperature (IAT) is less than 50°C (122°F).
* This DTC runs continuously when the above conditions are met.

P0118
* The engine is running for greater than 10 seconds.
OR
* The ignition is ON when the IAT is more than 0°C (32°F).
* This DTC runs continuously when the above conditions are met.

Conditions for Setting the DTC

P0117

The ECM detects that the ECT is more than 149°C (300°F) for greater than 5 seconds.

P0118

The ECM detects that the ECT is less than -39°C (-38°F) for greater than 5 seconds.

Action Taken When the DTC Sets

DTCs P0117 and P0118 are Type B DTCs.

Conditions for Clearing the MIL/DTC

DTCs P0117 and P0118 are Type B DTCs.

Circuit/System Verification

1. Ignition ON, observe the ECT Sensor parameter. The reading should be between -37 to +139°C (-35 to +282°F).
2. Operate the vehicle with the Conditions for Running the DTC. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records data.

Circuit/System Testing

Important: All electrical components and accessories must be turned OFF and allowed to power down.

1. Ignition OFF, disconnect the ECT harness connector at the ECT sensor.
2. Ignition OFF for 90 seconds, test for less than 5 ohms between the low reference circuit terminal A and ground.

^ If greater than the specified range, test the low reference circuit terminal A for an open/high resistance. If the circuit tests normal, replace the ECM.

3. Ignition ON, verify the scan tool ECT Sensor parameter is less than -39°C (-38°F).

^ If greater than the specified range, test the signal circuit terminal B for a short to ground. If the circuit tests normal, replace the ECM.

4. Install a 3A fused jumper wire between the signal circuit terminal B and the low reference circuit terminal A. Verify the scan tool ECT Sensor parameter is greater than 149°C (300°F).

^ If less than the specified range, test the signal circuit terminal B for a short to voltage or an open/high resistance. If the circuit tests normal, replace the ECM.

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

Component Testing

Measure and record the resistance of the ECT sensor at various ambient temperatures, then compare those measurements to the Temperature vs Resistance table.

Repair Instructions

* Engine Coolant Temperature Sensor Replacement