Diagnostic Instructions
| • | 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. |
DTC Descriptors
DTC P0115 03: Engine Coolant Temperature (ECT) Sensor Circuit Voltage Below ThresholdDTC P0115 07: Engine Coolant Temperature (ECT) Sensor Circuit Voltage Above Threshold
DTC P0116: Engine Coolant Temperature (ECT) Sensor Performance
DTC P0117: Engine Coolant Temperature (ECT) Sensor Circuit Low Voltage
DTC P0118: Engine Coolant Temperature (ECT) Sensor Circuit High Voltage
Typical Scan Tool Data
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 | 149°C (300°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+ | |||
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:
ECT | ECT Resistance | ECT Signal Voltage |
|---|---|---|
Cold | High | High |
Warm | Low | Low |
Conditions for Running the DTC
P0115 03, P0115 07, P0117, P0118
The ignition is ON.
P0116
| • | DTCs P0115, P0117, or P0118 are not set. |
| • | The engine speed is greater than 1,000 RPM. |
Conditions for Setting the DTC
P0115 03, P0117
The ECM detects the ECT voltage is less than 117 mV for greater than 1 second.
P0115 08, P0118
The ECM detects the ECT voltage is greater than 4.96 V for greater than 1 second.
P0116
The ECM detects the ECT sensor does not reach the minimum threshold within a calibrated time.
Action Taken When the DTC Sets
DTCs P0115, P0116, P0117, and P0118 are Type B DTCs.
Conditions for Clearing the DTC
DTCs P0115, P0116, P0117, and P0118 are Type B DTCs.
Diagnostic Aids
| • | 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. |
| • | If the engine has sat overnight, the IAT sensor and the ECT sensor values should display within 3°C (5°F). |
| • | 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. |
Reference Information
Schematic Reference
Connector End View Reference
Electrical Information Reference
DTC Type Reference
Powertrain Diagnostic Trouble Code (DTC) Type Definitions
Scan Tool Reference
Control Module References for scan tool information
Circuit/System Verification
- Engine running for 1 minute. Observe the DTC information with a scan tool. DTCs P0115, P0116, P0117 and P0118 should not set.
- Operate the vehicle within the Conditions for Running the DTC to verify the DTC does not reset. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records data.
Circuit/System Testing
- Ignition OFF, and the MAIN fuse removed, disconnect the ECT sensor.
- Test for less than 5 ohms between the low reference circuit terminal 2 and ground.
- Install the MAIN fuse. Ignition ON, verify the scan tool ECT sensor parameter is at -40°C (-40°F).
- Ignition ON, connect a 3A fused jumper wire between the signal circuit terminal 2 and ground. Verify the scan tool ECT sensor parameter is greater than 142°C (288°F).
- If all circuits test normal, test or replace the ECT sensor.
| ⇒ | 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 for a short to ground. If the circuit tests normal, replace the ECM. |
Caution: Do NOT use the low reference circuit in the component harness connector for this test. Damage to the control module may occur due to excessive current draw.
Note: If the fuse in the jumper wire opens, the signal circuit is shorted to a voltage and the sensor may be damaged.
| ⇒ | 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. |
Component Testing
Test and record the resistance between the signal circuit terminal 2 and the low reference circuit terminal 1 at various ambient temperatures. Compare those measurements to the Temperature Versus Resistance table and verify that the resistance is within 5 percent of the specification.
| ⇒ | If not within the specified range, replace the ECT sensor. |
Repair Instructions
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
| • | Control Module References for engine control module replacement, setup, and programming |
