DTC P0115, P0117, or P0118. Pontiac Vibe

For 1990-2009 cars only

Makes 🢒 Pontiac 🢒 2008 🢒 Vibe - FWD 🢒 Safety and Security 🢒 Supplemental Inflatable Restraints 🢒 DTC P0115, P0117, or P0118

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 P0115: Engine Coolant Temperature (ECT) Sensor Circuit

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

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

Diagnostic Fault Information

Circuit	Short to Ground	Open/High Resistance	Short to Voltage	Signal Performance
ECT Sensor Signal	P0115, P0117	P0115, P0118	P0115, P0118	P0116, P011B
Low Reference	--	P0110, P0113, P0115, P0118, P0120, P0123, P0220, P0223, P0450, P0453	--	P0116, P011B

Typical Scan Tool Data

ECT Sensor

Circuit	Short to Ground	Open	Short to Voltage
Operating Conditions: Engine operating in Closed Loop. Parameter Normal Range: -39 to +140°C (-39 to +284°F) Varies with coolant temperature.
ECT Sensor Signal	140°C (284°F)	-40°C (-40°F)	-40°C (-40°F)
Low Reference	--	-40°C (-40°F)	-40°C (-40°F)

Circuit

Short to Ground

Open

Short to Voltage

Operating Conditions: Engine operating in Closed Loop.

Parameter Normal Range: -39 to +140°C (-39 to +284°F) Varies with coolant temperature.

ECT Sensor Signal

140°C (284°F)

-40°C (-40°F)

Low Reference

-40°C (-40°F)

Circuit Description

The engine coolant temperature (ECT) sensor is a variable resistor that measures the temperature of the engine coolant. The powertrain control module (PCM) 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:

Temperature	ECT Resistance	ECT Signal Voltage
Cold	High	High
Warm	Low	Low

Conditions for Running the DTC

P0115, P0117, or P0118

•	The ignition is ON or the engine is operating.

•	The DTC runs continuously once the above condition is met.

Conditions for Setting the DTC

P0115

•	The temperature input is colder than -39°C (-39°F), greater than 4.91 volts, for greater than 0.5 seconds.

•	The temperature input is greater than 139°C (283°F), less than 0.18 volts, for greater than 0.5 seconds.

P0117

The temperature input is greater than 139°C (283°F), less than 0.14 volts, for greater than 0.5 seconds.

P0118

The temperature input is colder than -39°C (-39°F), greater than 4.91 volts, for greater than 0.5 seconds.

•	If the vehicle 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 circuit of the ECT sensor could set a DTC.

Reference Information

Schematic Reference

Engine Controls Schematics

Connector End View Reference

•	Powertrain Control Module Connector End Views

•	Engine Controls 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

Engine idling for 1 minute. Observe the DTC information with a scan tool. DTCs P0115, 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

Warning: An electric fan under the hood can start up even when the engine is not running and can injure you. Keep hands, clothing and tools away from any underhood electric fan.

Ignition OFF, disconnect the ECT sensor.
Test for less than 10 ohms between the low reference circuit terminal 1 and ground G104.

⇒	If greater than the specified range, test the low reference circuit for an open/high resistance, or for a short to voltage. If the circuit tests normal, replace the PCM.

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

⇒	If greater than the specified value, test the signal circuit for a short to ground. If the circuit tests normal, replace the PCM.

Install a 3A fused jumper wire between the signal circuit terminal 2 and the low reference circuit terminal 1. Verify the ECT sensor parameter is greater than 139°C (280°F).

⇒	If less than the specified value, test the signal circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the PCM.

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

Component Testing

Ignition OFF, disconnect the harness connector at the engine coolant temperature (ECT) sensor.

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

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.

⇒	If 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 control module replacement, setup, and programming