What it means
The ECM detects a circuit high fault on the engine oil pressure sensor/switch c circuit. Reading cannot be used reliably for control.
At a glance
- Usually lights the check-engine light
- The engine or gearbox may go into limp mode
How it works
Engine oil pressure sensor/switch C sends the ECM an electrical signal related to oil pressure. P2D90 sets when the C-circuit signal is above its expected range, often because the signal wire is shorted to battery voltage, the sensor is open, or a corroded connection interferes with the reading.
Common causes
Most likely first.
- Signal wire shorted to B+
- Open sensor
- Connector pins corroded - high contact resistance
Symptoms
- Oil-pressure warning light may be on
- Check-engine light may be on
- Oil-pressure gauge may read abnormally or fluctuate
How to diagnose it
- Save freeze-frame data and check sensor C live data to see whether the reported signal is persistently high or changes with operating conditions.
- Check the oil level and listen for engine noise; a high electrical signal does not establish that oil pressure is actually high or safe.
- Inspect sensor C wiring and connector for damage, corrosion, loose pins, and any signal wire contacting a powered wire.
- Use the manufacturer's wiring diagram to test the C signal circuit for a short to battery voltage and check connector continuity.
- If the harness passes, test sensor/switch C for an open or failed output and verify actual oil pressure by the manufacturer's procedure if indicated.
Common fixes
- Clean and secure corroded or loose sensor C connector terminals.
- Repair the C signal wire if it is shorted to battery voltage or otherwise damaged.
- Replace sensor/switch C if it is open or fails the manufacturer's test.
- Repair any confirmed oil-pressure fault found during mechanical checks.
Can I keep driving?
If the oil-pressure warning stays on or the engine becomes noisy, stop the engine and check the oil level; do not rely on the high circuit reading as proof that pressure is adequate. With no warning and normal engine sound, keep driving to a minimum and have the fault checked soon.
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.