P2266

Water in Fuel Sensor A Circuit Low

Q: 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.

Q: 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.

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.

Real-world scan data

Seen in

scans in the past year

Found in

<0.1%

of scans

<0.1%

of scans that found faults

Figures reflect only diagnostic scans recorded through our own apps and tools. Cars are typically scanned because a symptom or warning light prompted it, so these counts describe our scan records — not the incidence of faults in any model, and not the quality, reliability, or safety of any vehicle. No comparison between manufacturers or models is implied. All trademarks belong to their respective owners; no affiliation or endorsement is implied.

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.

Read & clear P2266 yourself

Scan your car, confirm the code, and clear it once it's fixed — with OBD DashX on your phone.

▶ Get it on Google Play

✓ Verified name — SAE J2012 / ISO 15031-6Guidance reviewed by OBD DashX