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 P0117 00: Engine Coolant Temperature (ECT) Sensor Circuit Low Voltage
DTC P0118 00: Engine Coolant Temperature (ECT) Sensor Circuit High Voltage
DTC P0119 00: Engine Coolant Temperature (ECT) Sensor Circuit Intermittent

### Diagnostic Fault Information

Circuit | Short to Ground | Open/High Resistance | Short to Voltage | Signal Performance
--- | --- | --- | --- | ---
ECT Sensor Signal | P0117 00 | P0118 00 | P0118 00 | P0116 00, P0119 00, P0128 00
Low Reference | -- | P0118 00 | P0118 00 | P0119 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 Signal | 150°C (302°F) | -40°C (-40°F) | -40°C (-40°F)
Low Reference | -- | -40°C (-40°F) | -40°C (-40°F)

### Circuit/System 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 V to the ECT 1 sensor signal circuit and a ground for the low reference circuit.

### Conditions for Running the DTC

#### P0117 00 and P0118 00

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

• | The battery voltage is greater than 9 V.

• | The IAT is warmer than -30°C (-22°F) or the IAT is colder than -30°C (-22°F) and the engine run time is greater than 120 s.

• | This DTC runs continuously within the enabling conditions.

#### P0119 00

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

• | The battery voltage is greater than 9 V.

• | DTC P0117 00 or P0118 00 are not set

### Conditions for Setting the DTC

#### P0117 00

The ECM detects that the ECT sensor 1 signal is less than 0.27 V, which is warmer than 137°C (279°F) for greater than 2 s.

#### P0118 00

The ECM detects that the ECT sensor 1 signal is greater than 4.96 V, which is colder than -39°C (-38°F) for greater than 2 s.

#### P0119 00

The ECM detects that the ECT sensor 1 signal has abruptly changed by a minimum of 5°C (9°F), warmer or colder for greater than 2 s.

### Action Taken When the DTC Sets

• | DTCs P0117 00, P0118 00 and P0119 00 are Type B DTCs

• | The cooling fans will be commanded ON.

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

### Conditions for Clearing the DTC

DTCs P0117 00, P0118 00 and P0119 00 are Type B DTCs

### 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. If the ignition has been OFF for 8 h or greater, the IAT, the ambient air temperature, and the ECT should be within 9°C (16°F) of each other. Ignition ON, observe the scan tool IAT Sensor, Ambient Air Temperature, and the ECT Sensor 1 parameters. Compare those sensor parameters to each other to determine if the condition is current.
2. Engine running, observe the ECT Sensor 1 parameter. The reading should be between -39 to +120°C (-38 to +248°F) depending on the current Ambient Air Temperature, the engine run time, and the vehicle operating conditions.
3. 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 B34A Engine Coolant Temperature (ECT) Sensor.
2. Ignition OFF, test for less than 5 Ω 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).

3. Ignition ON, verify the scan tool ECT Sensor 1 is greater than 4.8 V.

⇒ | If less than the specified range, test the signal circuit terminal 1 for a short to ground. If the circuit tests normal, replace the K20 Engine Control Module (ECM).

4. Install a 3 A fused jumper wire between the signal circuit terminal 1 and the low reference circuit terminal 2. Verify the scan tool ECT Sensor 1 is less than 0.3 V.

⇒ | If greater 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 K20 Engine Control Module (ECM).

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

### Component Testing

#### Static Test

Measure and record the resistance of the B34A Engine Coolant Temperature (ECT) Sensor at various ambient air temperatures, then compare those measurements to the link table.

### Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

• | Engine Coolant Temperature Sensor Replacement

• | Engine Control Module Replacement for ECM replacement, setup, and programming