P2266
Water in Fuel Sensor A Circuit Low
Fuel system (water-in-fuel sensor)
Generic OBD-II
Low
What it means
P2266 means the ECM sees an abnormally low voltage on the water-in-fuel sensor circuit — the sensor in the fuel filter/separator that detects water contamination. It's an electrical fault (usually a short to ground, bad connector, or failed sensor), so the engine typically drives normally, but the water-in-fuel warning is disabled until it's repaired.
Low
Can I keep driving? Yes — the engine runs normally, but the sensor that warns of water in the fuel is offline, so drain your fuel/water separator regularly until it's fixed.
Common symptoms
What you'll notice
- Check-engine light on
- Water-in-fuel warning light may stay on or stop working
- No change in how the engine runs, in most cases
Common causes
Most likely first
- Short to ground in the water-in-fuel sensor signal wire (reads low voltage)Likely
- Faulty water-in-fuel sensor at the fuel filter/separatorCommon
- Corroded or water-intruded connector at the fuel filter housingCommon
- Damaged wiring near the fuel filterLess often
- Faulty PCM/ECM (rare)Less often
How to diagnose & fix
Work through it in order
- Read freeze-frame data to see when the fault set.
- Inspect the water-in-fuel sensor connector at the fuel filter for corrosion or moisture.
- Check the signal wire for a short to ground and repair as needed.
- Test the sensor's resistance against the manufacturer's spec; replace it if out of range.
- Drain the fuel/water separator, then clear and re-test.
FAQ
Quick answers
Is it safe to drive with P2266?+
Usually yes — the engine runs normally. The catch is that the sensor warning you of water in the fuel is disabled, so drain your water separator regularly until it's repaired, especially on a diesel.
Can I just clear P2266?+
It will return until the wiring or sensor is fixed, since the ECM keeps seeing the low-voltage circuit fault.
Related codes
Often seen with P2266
Read & clear P2266 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