P0198 Engine Oil Temperature Sensor Circuit High

P0198 code - The Engine Oil Temperature (EOT) sensor is a variable resistor that measures the temperature of the engine oil. The Powertrain Control Module (PCM) supplies a 5-volt reference and ground to the sensors low reference signal circuit. When the oil temperature is low, the sensor resistance is high. When the oil temperature is high, the sensor resistance is low.


P0198 Engine Oil Temperature Sensor Circuit High


When monitored with the ignition on, battery voltage greater than 10.4 volts. Set condition the Engine Oil Temperature (EOT) sensor circuit voltage is above the acceptable calibrated threshold. Default action the MIL light will illuminate.

Possible causes:
  • Engine Oil Temperature signal circuit shorted to voltage.
  • Engine Oil Temperature signal circuit open/high resistance.
  • Sensor ground circuit open/high resistance.
  • Engine Oil Temperature sensor.
  • Powertrain Control Module (PCM).

Diagnose code P0198 Engine Oil Temperature Sensor Circuit High

Step 1. Check for an active condition
Turn the ignition on. Diagnose and repair any system voltage DTC before continuing with this test. With the scan tool, read DTC.

Is the DTC active or pending?

Yes, go to step 2.
No, perform the PCM intermittent condition.

Step 2. Check the EOT signal circuit for a short to voltage
Turn the ignition off, disconnect the EOT sensor harness connector. Turn the ignition on, measure the voltage between ground and the EOT signal circuit in the Engine Oil Temperature sensor harness connector

Is the voltage above 5.1 volts?

Yes, repair the EOT signal circuit for a short to voltage.
No, go to step 3.

Step 3. Check the EOT signal circuit for an open/high resistance
Turn the ignition off, disconenct the PCM harness connector. Measure the resistance of the EOT signal circuit between the Engine Oil Temperature sensor harness connector and PCM harness connector.

Is the resistance below 3.0 Ohms?

Yes, go to step 4.
No, repair the EOT signal circuit for an open or high resistance.

Step 4. Check the sensor ground circuit for an open/high resistance
Measure the resistance of the sensor ground circuit between the EOT sensor harness connector and PCM harness connector.

Is the resistance below 3.0 Ohms?

Yes, go to step 5.
No, repair the sensor ground circuit for an open or high resistance.

Step 5. Engine Oil Temperature sensor
Turn the ignition off, disconnect the EOT sensor harness connector. Connect a jumper between the EOT signal circuit and the sensor ground circuit at the EOT sensor harness connector. Turn the ignition on. The P0197 ENGINE OIL TEMPERATURE SENSOR CIRCUIT LOW DTC should be active or pending with the jumper in place.

Does the scan tool display as described above?

Yes, verify that there is good pin to terminal contact in the EOT sensor and Powertrain Control Module (PCM) connectors. Replace the Engine Oil Temperature sensor if no problems were found with the connectors.

No, go to step 6.

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