OBD Code P0198

Engine Oil Temperature Sensor High

What’s mean?

OBD2 Code P0198 Definition:
The Engine Oil Temperature (EOT) sensor is a thermistor device in which resistance changes with temperature. The electrical resistance of a thermistor decreases as the temperature increases and the resistance increases as the temperature decreases. The varying resistance affects the voltage drop across the sensor terminals and provides electrical signal to the Powertrain Control Module (PCM) corresponding to temperature. Thermistor-type sensors are considered passive sensor. A passive sensor is connected to a voltage divider network so that varying the resistance of the passive sensor causes a variation in total current flow. Voltage that is dropped across a fixed resistor in a series with the sensor resistor determines the voltage signal at the PCM. This voltage signal is equal to the reference voltage minus the voltage drop across the fixed resistor. The EOT sensor measures the temperature of the engine oil. The sensor is typically threaded into the engine oil lubrication system. The PCM can use the EOT sensor input to determine the following: – On variable cam timing (VCT) applications the EOT input is used to adjust the VCT control gains and logic for camshaft timing. – The PCM can use the EOT sensor input in conjunction with other PCM inputs to determine oil degradation – The PCM can use EOT sensor input to initiate a soft engine shutdown. To prevent engine damage from occurring as a result of high oil temperature, the PCM has the ability to initiate a soft engine shutdown. Whenever engine RPM exceeds a calibrated level for a certain period of time, the PCM will begin reducing power by disabling engine cylinders.

Symptoms

Possible sumptoms of P0198
– Engine Light ON (or Service Engine Soon Warning Light) – Lack/Loss of Power – Engine Surge

Possible Causes

Possible causes of P0198
– Engine not at operating temperature. – Cooling system problem of stuck thermostat. – EOT circuit failure. – Bad EOT sensor – Damaged PCM. The Error code is generally activated on detection of the following conditions: Indicates EOT signal voltage is hign (low temperature).

Possible Solutions

1. Key On Engine Off 2. Monitor the Engine Oil Temperature in live data 3. Tap EOT sensor and wiggle the wire harness connector to simulate road shock and wiggle the wiring from the sensor to the PCM watching the sensor on AE 4. If the EOT sensor value defaults to 100*C(212*F) look at the connectors and wiring from the sensor to the PCM. Disconnect EOT sensor and PCM harness connectors. Inspect for damage, loose or pushed-out pins, loose or poorly crimped wires