For 1990-2009 cars

### 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 P0116 00: Engine Coolant Temperature (ECT) Sensor Performance

### Diagnostic Fault Information

Circuit | Short to Ground | High Resistance | Open | Short to Voltage | Signal Performance
--- | --- | --- | --- | --- | ---
ECT Sensor 1 Signal | P0117 00 | P0118 00 | P0118 00 | P0118 00* | P0116 00, P0119 00, P0128 00
Low Reference | -- | P0118 00 | P0118 00 | P0118 00* | P0116 00, P0128 00

### Typical Scan Tool Data

#### ECT Sensor 1

Circuit | Short to Ground | Open | Short to Voltage
--- | --- | --- | ---
Operating Conditions: The ignition is ON, or the engine is running Parameter Normal Range: Varies with ambient air temperature, within a range of -39 to +120°C (-38 to +248°F)
ECT Sensor 1 Signal | 140°C (284°F) | -40°C (-40°F) | -40°C (-40°F)
Low Reference | -- | -40°C (-40°F) | -40°C (-40°F)

### Circuit/System Description

The ECT sensor 1 is a variable resistor that measures the temperature of the engine coolant. The engine control module (ECM) supplies 5 V to the ECT sensor 1 signal circuit and supplies a ground for the low reference circuit.

The purpose of this diagnostic is to analyze the performance of the ECT sensor 1 by comparing the response and the range of the sensor signal to two distinct models under various operating conditions.

• | The first model verifies that the sensor is not stuck in range.

• | The second model verifies that the sensor is within an acceptable operating range of the calculated ECT. Both models use various parts of the information derived from the following inputs:

• | Ambient air temperature

• | ECT

• | Engine OFF time

• | Intake air temperature (IAT)

• | Engine OFF time

### Conditions for Running the DTC

#### P0116 00

• | The ignition is ON, or the engine is running.

• | DTC P0117 00 or P0118 00 are not set

• | This DTC runs continuously within the enabling conditions.

### Conditions for Setting the DTC

#### P0116 00 Engine Running, Sensor Signal Stuck Test

• | The ECT back up value minus the ECT back up value at engine start, is not within range of the calibrated model.

• | The measured ECT 1 minus the measured ECT 1 at engine start, is not within range of the calibrated model.

#### P0116 00 Engine Running, Sensor Within Range Test

• | The ECT 1 at engine start is not within range of the calibrated model.

• | The ECT 1 at engine start minus the IAT at engine start is not within range of the calibrated model.

### Action Taken When the DTC Sets

• | DTC P0116 00 is a Type B DTC

• | The cooling fans will be commanded ON.

• | The A/C compressor will be commanded OFF.

### Conditions for Clearing the DTC

DTC P0116 00 is a Type B DTC

### Reference Information

#### Schematic Reference

Engine Controls Schematics

#### Connector End View Reference

Component Connector End Views

#### Description and Operation

Cooling System Description and Operation

#### 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. Verify that DTC P0111 00, P0112 00, P0113 00, P0114 00, P0117 00, P0118 00, P0119 00 or P0128 00 is not set.

⇒ | If any of the 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

Note: You must perform the Circuit/System Verification before proceeding with Circuit/System Testing.

1. Ignition OFF, disconnect the harness connector at the B34A Engine Coolant Temperature (ECT) Sensor.
2. Ignition ON, clear the DTC information with a scan tool.
3. Ignition OFF, test for less than 5 Ω of resistance between the low reference circuit terminal 2 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 K20 Engine Control Module (ECM).

4. Ignition ON, verify the scan tool ECT Sensor 1 parameter is at -40°C (-40°F).

⇒ | If greater than the specified range, test the signal circuit for a short to ground. If the circuit tests normal, replace the K20 Engine Control Module (ECM).

5. Ignition ON, clear the DTC information with a scan tool.

Note: 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 1 A fused jumper wire between the signal circuit terminal 1 and the low reference circuit terminal 2. Verify the scan tool ECT sensor 1 parameter is greater than 128°C (262°F).

⇒ | If less than specified range, test the signal circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the K20 Engine Control Module (ECM).

7. If all circuits test normal, test or replace the B34A Engine Coolant Temperature (ECT) Sensor.

### Component Testing

#### Static Test

1. Ignition OFF, disconnect the harness connector at the B34A Engine Coolant Temperature (ECT) Sensor.

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

2. Test the B34A Engine Coolant Temperature (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% of the specification.

⇒ | If not within the specified range, replace the B34A Engine Coolant Temperature (ECT) Sensor.

### Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

• | Engine Coolant Temperature Sensor Replacement

• | Control Module References for ECM replacement, setup, and programming