GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Holden 🢒 2008 🢒 Viva 🢒 Safety and Security 🢒 Supplemental Inflatable Restraints 🢒 DTC P0115

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 Descriptor

DTC P0115: Engine Coolant Temperature (ECT) Sensor Circuit

Typical Scan Tool Data

ECT Sensor

Circuit

Short to Ground

Open

Short to Voltage

Operating Conditions: Engine operating in Closed Loop.

Parameter Normal Range: Varies with ambient temperature.

ECT Sensor Signal

129°C (264°F), 0.0 Volts

-40°C (-40°F), 5.0 Volts

-40°C (-40°F), 5.0 Volts*

Low Reference

--

-40°C (-40°F), 5.0 Volts

--

* ECM or 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
    • DTCs P0117, P0118, and P2610 are not set.
    • The engine is operating.
    • The ignition has been off for greater than 6 hours before vehicle is started.
    • The DTC runs once per ignition cycle once the above conditions are met.

Conditions for Setting the DTC

The ECM does not detect an engine coolant temperature (ECT) sensor change of greater than 3°C (5°F).

Action Taken When the DTC Sets
    • DTC P0115 is a Type B DTC.
    • The ECM commands the cooling fans ON.

Conditions for Clearing the MIL/DTC

DTC P0115 is a Type B DTC.

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. Refer to Temperature Versus Resistance.
    • Inspect for the correct operation of the engine cooling system and verify the correct coolant level.

Reference Information

Schematic Reference

Engine Controls Schematics

Connector End View Reference

Component Connector End Views

Electrical Information Reference

    •  Circuit Testing
    •  Connector Repairs
    •  Testing for Intermittent Conditions and Poor Connections
    •  Wiring Repairs

DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions

Scan Tool Reference

Control Module References for scan tool information

Circuit/System Verification
  1. Engine running, observe the DTC information with a scan tool. DTCs P0112, P0113, P0117, P0118, P0125, or P0128 should not set:
    2. ⇒If any DTCs are set, refer to Diagnostic Trouble Code (DTC) List - Vehicle.
  2. 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
  1. Ignition OFF, disconnect the harness connector at the ECT sensor.
  2. Ignition ON, clear the DTC information with a scan tool.
  3. Ignition OFF, test for less than 5 ohms of resistance between the low reference circuit terminal A or 2 and ground.
    4. ⇒If greater than the specified range, test the low reference circuit for an open/high resistance. If the circuit tests normal, replace the ECM.
  4. Ignition ON, clear the DTC information with a scan tool.
  5. Verify the scan tool ECT sensor parameter is at -40°C (-40°F).
    6. ⇒If greater than the specified range, test the signal circuit for a short to ground. If the circuit tests normal, replace the ECM.

    Important: If the fuse in the jumper wire opens, the signal circuit is shorted to a voltage and the sensor may be damaged.

  6. Install a 1A fused jumper wire between the signal circuit terminal B or 1and the low reference circuit terminal A or 2. Verify the scan tool ECT sensor parameter is greater than 128°C (262°F).
    7. ⇒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.
  7. If all circuits test normal, test or replace the ECT sensor.

Component Testing
  1. Ignition OFF, disconnect the harness connector at ECT sensor.

    2. 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 Versus Resistance table and verify that the resistance is within 5 percent of the specification.
    3. ⇒If the resistance Vs. temperature is not within the specified range, replace the ECT sensor.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

    •  Engine Coolant Temperature Sensor Replacement
    •  Control Module References for engine control module replacement, setup, and programming