P2266: Water in Fuel Sensor A Circuit Low

P2266 is set when the signal line of water-in-fuel sensor A stays below its valid range, typical of a grounded signal wire or of a conductive path that should not be there. Ford documents the code on 2017 and 2018 Super Duty trucks with the 6.7L diesel built up to 15 March 2018: bulletin 18-2133 links P2266, P2269 and P1140 with a lit water-in-fuel lamp to water entering connector C3080 at the sensor, which sits between tank and frame rail. The procedure checks the sensor across pins 1 and 2 for 795 to 815 kOhm, replaces it if out of range, then dries and wraps the connector. As water itself conducts, a wet plug can fake both a low circuit and a water alarm. P2267 is the high side, P2264 the general circuit code.

Low severity. Can I keep driving?You can normally keep driving. If it affects the fuel level, do not trust the gauge and refuel earlier than usual.

Symptoms

Water-in-fuel lamp on although no water is in the separator
Often stored together with P2269

Most likely causes

Water intrusion into the sensor connector bridging signal and ground
Sensor with internal resistance outside specification
Signal wire chafed against the frame and shorted to ground

What to check, in order

Start with the simplest. You can tick off each step.

Check the connector and wiring
With the connector unplugged, check whether the signal wire is making contact with ground.
Use live data to compare the reading with actual conditions
Measure power, ground, and signal
Replace the sensor if the circuit is good

Good to know

Repair difficulty: easy

What each character of P2266 means

P: Powertrain: engine and transmission
2: Generic code: same on every make
2: Fuel injection
66: Specific fault in that system

Frequently asked questions

Can I keep driving with code P2266?

You can normally keep driving. If it affects the fuel level, do not trust the gauge and refuel earlier than usual.

What causes code P2266?

The most common causes are: water intrusion into the sensor connector bridging signal and ground; sensor with internal resistance outside specification; signal wire chafed against the frame and shorted to ground.

Related codes

Sources

Values and procedures vary by manufacturer. If it affects brakes, steering, fuel or high voltage, see a professional. Updated: 2026-11-04. How we build these pages.