P0118

DTC 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 prior to using this diagnostic procedure. Initial Inspection and Diagnostic Overview

TYPICAL SCAN TOOL DATA

ECT Sensor Temperatures:

CIRCUIT/SYSTEM DESCRIPTION
The engine coolant temperature (ECT) sensor is a variable resistor, that measures the temperature of the engine coolant. The control module supplies 5 volts to the ECT signal circuit and a ground for the ECT low reference circuit. When the ECT is cold, the sensor resistance is high. When the ECT increases, the sensor resistance decreases. With high sensor resistance, the control module detects a high voltage on the ECT signal circuit. With lower sensor resistance, the control module detects a lower voltage on the ECT signal circuit. If the control module detects an excessively low ECT signal voltage, which is a high temperature indication, DTC P0117 sets. If the control module detects an excessively high ECT signal voltage, which is a low temperature indication, DTC P0118 sets.

CONDITIONS FOR RUNNING THE DTC

P0117
- The engine run time is more than 3 seconds. Or The ignition is ON and the IAT parameter is less than 90°C (194°F).
- The diagnostic runs continuously when the above conditions are met.

P0118
- The engine is running for more than 30 seconds. Or The ignition is ON and the IAT parameter is more than 0°C (32°F).
- The diagnostic runs continuously when the above conditions are met.

CONDITIONS FOR SETTING THE DTC

P0117
The control module detects that the ECT sensor parameter is more than 139°C (282°F) for more than 24 seconds.

P0118
The control module detects that the ECT sensor parameter is less than -37°C (-35°F) for more than 24 seconds.

ACTION TAKEN WHEN THE DTC SETS
DTC P0117 and P0118 are Type B DTCs

CONDITIONS FOR CLEARING THE DTC
DTC P0117 and P0118 are Type B DTCs

DIAGNOSTIC AIDS
- An overheating condition may cause this DTC to set.
- After starting the engine, the ECT sensor temperature should rise steadily to about 90°C (194°F) then stabilize after the thermostat opens.
- If a short to a separate voltage source occurs this DTC may set and damage the ECT sensor.

CIRCUIT/SYSTEM TESTING
1. Ignition OFF, disconnect the harness connector at the ECT sensor.

IMPORTANT:
- The cooling fans are commanded ON when certain DTCs are set.
- If shorted to voltage occurs, the ECT sensor may be damaged.

2. Ignition OFF, test for less than 5 ohm of resistance between the low reference circuit terminal A and ground.
- If greater than the specified range, test the low reference circuit for an open/high resistance. If the circuit tests normal, replace the control module.
3. Ignition ON, verify the scan tool ECT parameter is less than -38°C (-36°F).
- If greater than the specified range, test the signal circuit terminal A for a short to ground. If the circuit tests normal, replace the control module.
4. Install a 3A fused jumper wire between the signal circuit terminal A and the low reference circuit terminal B. Verify the scan tool ECT parameter is greater than 138°C (280°F).
- 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 control module.
5. If all circuits test normal, test or replace the ECT sensor.

REPAIR INSTRUCTIONS
Perform the Diagnostic Repair Verification after completing the repair.
- Engine Coolant Temperature Sensor Replacement
- Control Module References for engine control module (ECM) replacement, setup, and programming Verification Tests