What it means
Same as P0520 with the signal voltage above the plausible range - usually a short to supply or sensor failure that pegs the output high.
At a glance
- Usually lights the check-engine light
How it works
Oil pressure sensor or switch A sends a signal to the control module so it can monitor engine oil pressure. P0523 sets when the sensor circuit signal is above its expected range, which can happen if the signal wire is shorted to voltage or the sensor fails high. An unusually high gauge reading may therefore be an electrical error rather than actual high oil pressure.
Common causes
Most likely first.
- Oil pressure sensor or switch faulty
- Signal wire shorted to voltage
- Loose, corroded, or damaged connector
- Open or damaged wiring
Symptoms
- Check-engine light on
- Oil-pressure warning light may illuminate
- Oil-pressure gauge may read unusually high or stay at one end
How to diagnose it
- Record freeze-frame data and check the live reading and gauge behavior to confirm whether the high indication is steady or intermittent.
- Inspect sensor A’s connector for looseness, corrosion, or damage that could interrupt the signal.
- Trace the signal wire for damaged insulation or contact with a powered wire.
- Test the signal circuit for a short to voltage and check wiring and connector continuity against the manufacturer’s specification.
- If the circuit is sound but the signal remains high, test oil pressure sensor or switch A using the manufacturer’s procedure.
Common fixes
- Secure or repair a loose or corroded sensor A connector.
- Repair signal wiring shorted to voltage or damaged by contact with a powered wire.
- Repair an open or damaged section of the oil-pressure sensor circuit.
- Replace oil pressure sensor or switch A if it fails testing with a verified circuit.
Can I keep driving?
A high gauge reading alone may be an electrical fault, but do not ignore an oil-pressure warning light or unusual engine noise. If either occurs, stop the engine and have actual oil pressure checked before driving further.
A code shows where the control module detected a fault, not always which part failed. Check the causes in order and confirm with a test before replacing parts. Have several codes? Check them together
This is a generic code: it means the same on every make. The car’s maker may add more detail in its own service information.