Oil Level Sensor: Description and Operation

The engine oil level switch is a simple float switch that is grounded when the engine oil level is OK. When the ignition is first turned on, the PCM commands the Low Oil Level lamp on for approximately 3 seconds in order to to test the bulb. The PCM also checks the engine oil level switch circuit at startup. If the engine has been running, the PCM performs a test routine based upon the ECT in order to ensure that the engine oil has drained back into the sump before checking the state of the engine oil level switch. If the ECT is between 15°C (59°F) and 130°C (266°F), the PCM compares the ECT at the last key-off to the ECT at the current key-on. If the difference between the temperature values is at least 12°C (54°F), the PCM tests the engine oil level.