P2559
Engine Coolant Level Sensor/Switch Circuit High
Engine cooling
Generic OBD-II
Low
What it means
P2559 means the engine coolant level sensor circuit is reading an abnormally high voltage, which the ECM interprets as a circuit fault. It's usually a failed sensor, an open circuit, or corroded wiring — but always confirm the coolant is genuinely full first, because a real low-coolant condition risks overheating.
Low
Can I keep driving? Usually drivable — this is a coolant-level sensor circuit fault. But confirm the coolant is actually full first, because genuine low coolant risks overheating.
Common symptoms
What you'll notice
- Check-engine light on
- Coolant level warning light or message (possibly false)
- No change in how the engine runs in most cases
- Warning may stay on even when the reservoir is full
Common causes
Most likely first
- Faulty engine coolant level sensor/switchLikely
- Open circuit or short to voltage producing a high readingCommon
- Corroded or loose sensor connectorCommon
- Genuinely low coolant levelLess often
- Poor sensor groundLess often
How to diagnose & fix
Work through it in order
- Check the actual coolant level in the reservoir first and top up if low.
- Read freeze-frame data and confirm the high-circuit reading.
- Inspect the sensor connector and wiring for opens, shorts to voltage, and corrosion.
- Verify the sensor ground and test the sensor/switch operation.
- Replace the coolant level sensor if faulty, then clear and re-test.
FAQ
Quick answers
Is it safe to drive with P2559?+
Usually yes if the coolant is genuinely full — it's often just a sensor or wiring fault. But never ignore a low-coolant warning without confirming the actual level, since overheating causes real engine damage.
Can I just clear P2559?+
It will return unless the sensor, its wiring, or an actual low-coolant condition is corrected.
Related codes
Often seen with P2559
Read & clear P2559 yourself
Scan your car, confirm the code, and clear it once it's fixed — with OBD DashX on your phone.
✓ Verified name — SAE J2012 / ISO 15031-6Guidance reviewed by OBD DashX