P0198

P0198-ENGINE OIL TEMPERATURE SENSOR CIRCUIT HIGH

For a complete wiring diagram, refer to the Wiring Information.





Theory of Operation

The Engine Oil Temperature (EOT) sensor is a variable resistor that measures the temperature of the engine oil. It operates as a typical two wire sensor. The Powertrain Control Module (PCM) supplies the sensor with a 5-Volt reference and a sensor ground circuit. When the oil temperature is low, the sensor resistance is high. When the oil temperature is high, the sensor resistance is low.

- When Monitored:
With the ignition on and no Battery voltage or ASD Relay DTCs active.

- Set Condition:
The Engine Oil Temperature Sensor circuit voltage at the Powertrain Control Module (PCM) is greater 4.9 volts for five seconds. Two Trip Fault. Three good trips to turn off the MIL.





Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. Pre-Diagnostic Troubleshooting Procedure.

Diagnostic Test

1. ACTIVE DTC
1. Start the engine and allow it to reach normal operating temperature.

WARNING:
When the engine is operating, do not stand in direct line with the fan. Do not put your hands near the pulleys, belts or fan. Do not wear loose clothing. Failure to follow these instructions may result in possible serious or fatal injury.

NOTE: Diagnose and repair any system voltage DTCs before continuing with this test.

2. With the scan tool, select View DTCs.

Is the DTC Active at this time?

Yes

- Go To 2

No

- Perform the INTERMITTENT CONDITION diagnostic procedure. Intermittent Condition Test.

2. ENGINE OIL TEMP SENSOR
1. With the scan tool, clear the DTC.
2. Turn the ignition off.
3. Disconnect the Engine Oil Temp Sensor harness connector.
4. Connect a jumper wire between the Engine Oil Temp Signal circuit and the Sensor ground circuit in the Engine Oil Temp Sensor harness connector.
5. Ignition on, engine not running.

NOTE: The sensor voltage should be approximately 0.0 Volts (plus or minus.1 of a Volt) with the jumper wire in place.

Does the scan tool display the voltage as described above?

Yes

- Verify that there is good pin to terminal contact in the EOT Sensor and Control Module connectors. Replace the Engine Oil Temperature Sensor if no problems were found with the connectors. .
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.

No

- Go To 3

NOTE: Remove the jumper wire before continuing.


3. ENGINE OIL TEMP SIGNAL CIRCUIT SHORTED TO VOLTAGE
1. Turn the ignition off.
2. Disconnect the PCM harness connector.
3. Ignition on, engine not running.
4. Measure the voltage on the Engine Oil Temp Signal circuit in the Engine Oil Temp Sensor harness connector.

Is there any voltage present?

Yes

- Repair the short to voltage in the Engine Oil Temp Signal circuit.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.

No

- Go To 4

4. ENGINE OIL TEMP SIGNAL CIRCUIT OPEN
1. Turn the ignition off.
2. Measure the resistance of the Engine Oil Temp Signal circuit from the Engine Oil Temp Sensor harness connector to the appropriate terminal of the PCM harness connector.

Is the resistance below 5.0 Ohms?

Yes

- Go To 5

No

- Repair the open or excessive resistance in the Engine Oil Temp Signal circuit.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.

5. SENSOR GROUND CIRCUIT OPEN
1. Measure the resistance of the Sensor ground circuit from the Engine Oil Temp Sensor harness connector to the appropriate terminal of PCM harness connector.

Is the resistance below 5.0 Ohms?

Yes

- Go To 6

No

- Repair the open or excessive resistance in the Sensor ground circuit.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.

6. POWERTRAIN CONTROL MODULE (PCM)
1. Using the wiring diagram/schematic as a guide, inspect the wiring and connectors between the Engine Oil Temperature Sensor and the Powertrain Control Module (PCM).
2. Look for any chafed, pierced, pinched or partially broken wires.
3. Look for broken, bent, pushed out or corroded terminals. Verify that there is good pin to terminal contact in the Sensor and Control Module harness connectors.
4. Perform any Technical Service Bulletins that may apply.

Were there any problems found?

Yes

- Repair as necessary.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.

No

- Replace and program the Powertrain Control Module. .
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.