OBD-II Trouble Code Description for P0197 Lexus

Engine Oil Temperature Sensor Low

What does this mean?

OBD2 Code P0197 Lexus 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 OBD code P0197 Lexus
– Engine Light ON (or Service Engine Soon Warning Light) – Lack/Loss of Power – Engine Surge

Causes

Possible causes of OBD code P0197 Lexus
– 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 low (high temperature).

Possible Solutions

1. Disconnect the EOT sensor harness connector 2. Check for opposite failure with EOT disconnected 3. If DTC P0198 Lexus is present replace EOT sensor