P0523

The P0523 code means the voltage signal from the engine oil pressure sensor is above the maximum expected threshold. This is the opposite of P0522 (low voltage) and typically indicates an open circuit condition rather than an actual high-pressure problem. When a sensor wire breaks or a connector comes loose, the PCM's internal pull-up resistor pulls the signal to maximum voltage, which is what triggers this code.

You'll likely see your oil pressure gauge pegged at maximum, or in vehicles without a gauge, the Check Engine light will be your primary indicator. Unlike the low-voltage code P0522, this code is generally less of an immediate safety concern because an open circuit (the most common cause) is unlikely to indicate actual dangerously high oil pressure. However, it still means the PCM has lost the ability to monitor your oil pressure, so a real problem could go undetected.

Start diagnosis by checking the connector at the oil pressure sensor — vibration can cause it to work loose over time. Push it firmly onto the sensor and see if the code clears. If the connector looks good, check the wiring for breaks, especially where the harness bends or passes near hot exhaust components. The sensor itself is also a common cause and is inexpensive to replace. As with any oil pressure code, it's good practice to verify actual pressure with a mechanical gauge for peace of mind.

Severity

Symptoms

• •Oil pressure gauge reads maximum or pegged at the high end
• •Oil pressure warning light may be on or off depending on vehicle
• •Check Engine light is on
• •No noticeable change in engine performance
• •Oil pressure reading doesn't change with RPM or temperature

Likely Causes

Estimated Cost

Common Fixes

1. Replace the oil pressure sensor/sending unit
2. Reconnect or replace the oil pressure sensor connector
3. Repair open circuit or broken wiring in the oil pressure circuit
4. Clean corroded connector pins and ensure proper seating

Shop Parts

Related Codes