Water in Fuel Indicator
Indicates that the fuel system has detected water in the fuel.
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What it means (plain English)
The computer monitors for water content in the diesel fuel. If it detects more than about 0.05% water (roughly 50 parts per million), it throws this code to warn you of potential problems such as fuel system damage or poor combustion.
What the computer is actually seeing
The sensor measures electrical resistance; higher water content lowers resistance. The computer sees resistance values that indicate water presence. When resistance drops below a certain threshold, the code triggers.
What a healthy reading looks like
Less than 0.05% water in fuel; resistance values generally above 30 ohms in the sensor.
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.
- 11. Inspect fuel tank for any leaks or signs of contamination.
- 22. Check the connectors and wiring to the water separator sensor for corrosion or damage. Repair as needed.
- 33. Measure the resistance from the water sensor. If resistance is below 30 ohms, the sensor is likely faulty; replace if necessary.
- 44. Drain the fuel system to remove any water. Recheck water content after draining.
- 55. Re-test fuel quality after repairs; if code returns, further investigation into fuel source is needed.
Common causes
- Contaminated fuel
- Faulty water in fuel sensor
- Fuel tank corrosion
- Leaky fuel lines
Typical repair cost
$$$
Related codes
Frequently asked questions
Is it safe to drive with this code?
No, driving with this code can cause engine damage or performance issues because water in the fuel can affect combustion.
Will this code come back after fixing?
If the source of the water is addressed and the sensor is replaced, the code should not return.
Why does this code pair with other codes?
Commonly, water in fuel can impact fuel delivery or combustion, triggering other related fault codes.
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