Engine Oil Pressure Sensor/Switch Circuit Malfunction
The PCM has detected an abnormal reading from the engine oil pressure sensor (switch). If this code is present, or if the red oil pressure warning indicator is illuminated, shut the engine off IMMEDIATELY! Catastrophic engine failure could result if this condition is not rectified at once.
Code Set Parameters
The PCM monitors oil pressure on some late model vehicles, anytime the engine is running. Variations in oil pressure that exceed a predetermined maximum, or fall below a minimum pound-per-square-inches of pressure, will cause a trouble code to be stored and a service engine soon lamp to be illuminated. Most models will also display a red low oil pressure warning lamp.
The service engine soon lamp and/or red low engine oil pressure warning lamp may be illuminated and a code will be stored in the PCM. Failure to turn the engine off during a low oil pressure situation will cause engine noise and possibly catastrophic engine failure.
Technicians report that the most common cause of this code comes from lack of engine maintenance. Failure to change your engine oil at regular intervals may result in a low oil level/oil pressure condition. Most engines “burn” at least one quart of engine oil every 3,000-miles. Other causes include a faulty oil pressure sensor, shorted or open wiring in the oil pressure sending unit circuit, and mechanical engine failure.
Oil pressure sensor replacement is common but not automatic. Many times an oil pressure sensor is replaced to correct a condition that has been prolonged too long. If internal engine failure has occurred, due to a low oil level/oil pressure condition, an oil sending unit may appear to rectify the situation for a time but the low oil pressure condition may return when the engine reaches normal operating temperature.
- The oil pressure sending unit is typically a pressure to contact switch which is threaded into an oil passage of the engine block
- A low voltage (normally 5-volts) signal is supplied to the oil pressure sensor
- This low voltage signal is grounded through the sensor
- As oil pressure increases in the engine, the sensor resistance decreases allowing the voltage input signal to the PCM to increase
- The PCM is programmed to verify a minimum and maximum voltage reading from the oil pressure sensor in order to constantly monitor engine oil pressure.
Several tools will be instrumental in successfully diagnosing this code
- A suitable OBD-II scanner (or code reader), a digital volt/ohmmeter, and a manual oil pressure gauge will be most helpful in performing a successful diagnosis
Begin with a visual inspection of all wiring and connectors
- Repair or replace damaged, disconnected, shorted, or corroded wiring, connectors, and components as necessary
- Always retest the system after repairs are completed to ensure success.
If all system wiring, connectors, and components (Including fuses) appear to be in normal working order, connect the scanner (or code reader) to the diagnostic connector and record all stored codes and freeze frame data
- This information can be extremely helpful in diagnosing intermittent conditions that may have contributed to this code being stored
- Continue by clearing the code and operating the vehicle to see if it returns
- This will help to determine whether or not the malfunction is intermittent
After the codes are cleared, test drive the vehicle to see if the code returns
- If the code fails to immediately return, you may have an intermittent condition
- Intermittent conditions can prove to be quite a challenge to diagnose and in extreme cases may have to be allowed to worsen before a correct diagnosis can be made
If engine oil pressure is excessive, suspect a faulty oil pressure sensor or clogged oil filter.
Make sure that the engine is filled to the proper level with suitable engine oil.
To diagnose the low oil pressure condition, connect the scanner or code reader and make a note of all stored trouble codes and applicable freeze frame data
- Clear the codes and shut the engine off
- Connect the manual oil pressure gauge to the engine
- Start the engine and check for leaks Allow the engine to reach normal operating temperature and make a note of the actual oil pressure reading at idle, 1,200 RPMS, and 2,500 RPMs
- Compare your findings with the manufacturer’s specifications and make engine repairs as necessary.
If the engine oil pressure is within acceptable specifications, disconnect the oil pressure sensor connector and perform a resistance test on the sensor
- Compare your findings with manufacturer’s specifications and replace the oil pressure sensor as needed
- If the electrical connector face of the oil pressure sensor is contaminated with engine oil, suspect a faulty sensor (it is leaking and should be replaced).
If the sensor is within acceptable specifications, disconnect the PCM connector and perform a continuity/resistance test on all wiring circuits
- Compare your findings with manufacturer’s specifications and repair open or shorted wiring as necessary
- PCM failure is rare as a cause of this condition