Water in Fuel Sensor Fault
Indicates a problem with the water in fuel sensor signal.
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What it means (plain English)
The water in fuel sensor is supposed to detect if there's water mixed with the diesel fuel. If it's faulty, it won't send the right signals to the engine control module (ECM), which could lead to fuel contamination and engine issues.
What the computer is actually seeing
The ECM expects a voltage signal that indicates the water level in the fuel. Typically, it should fluctuate around 1-2 volts when the sensor is functioning correctly. A reading lower than 0.5V or higher than 4.5V can signal a fault.
What a healthy reading looks like
Normal sensor voltage should be between 1-2 volts. If no water is present, the reading should be stable around 1V.
Guided diagnostic — the DiagCoach way
Don't just throw parts at it. Walk through these in order — each step tells you whether to keep going or stop and fix what you found.
- 1Check the wiring and connectors for damage or corrosion. Repair as necessary. Decision: If wiring is intact, continue to step 2.
- 2Verify that there is no water present in the fuel filter or separator. Drain if needed. Decision: If water is found, resolve the contamination issues before proceeding.
- 3Test the voltage at the water in fuel sensor connector with the key in the 'on' position. Expected voltage is 1-2V. Decision: If voltage is out of range, replace the sensor.
- 4If the sensor is reading correctly, check for fault codes related to the ECM or other components that could affect sensor performance.
Common causes
- Faulty water in fuel sensor
- Corroded or damaged wiring harness
- Bad connector at the sensor
- Water contamination in fuel separator
Typical repair cost
$$ ($120-$300)
Related codes
Frequently asked questions
Is it safe to drive with this code active?
It's not recommended to drive long distances as water in fuel can damage the engine.
Will this code come back after I fix it?
If the underlying issue is resolved, the code should clear after a few driving cycles.
Why does this code sometimes pair with other codes?
Water in fuel can affect multiple systems, leading to various fault codes related to fuel and engine problems.
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