Symptom
Water in fuel warning light
A diesel warning, usually a droplet symbol, fed by a float in the bottom of the fuel filter housing. Water separates out of diesel and collects there because it is heavier, and the sensor is watching for the level that would let it reach the injection pump. Draining the filter bowl is free, takes minutes and is the correct first response — modern high-pressure injection equipment is destroyed by water rather than merely upset by it. A fault in the sensor circuit can raise this warning when there is no water at all, which is worth knowing but is not a reason to ignore it.
Also described as: water in fuel light, water in diesel warning, fuel filter water light, drain fuel filter light, water droplet light, چراغ اب در گازوئیل, اب در باک گازوئیل, چراغ اب سوخت, luz agua en gasoil, testigo agua combustible, aviso agua diesel, لمبة ماء في الديزل, تحذير ماء في الوقود, علامة ماء في السولار
Some causes mean you should stop driving
1 of the 6 codes that produce this symptom indicate a fault where continuing to drive risks damage or is unsafe. If the symptom is sudden or severe, treat it as one of those until a scan says otherwise.
What this usually means
Drain the filter bowl. It is free, takes minutes, and is the correct first response — modern high-pressure diesel injection equipment is destroyed by water rather than merely upset by it, and the cost of being wrong in the other direction is enormous.
The mechanism is simple and worth knowing because it explains why the warning exists at all. Water is heavier than diesel and separates out of it, collecting in the bottom of the filter housing. A float there watches for the level that would let water reach the injection pump. Diesel fuel is also the lubricant for that pump and for the injectors, so water passing through does not dilute a lubricant — it removes it, and the resulting wear happens in minutes at the pressures involved.
Where the water comes from is worth pursuing after the immediate drain. Condensation in a tank that is habitually run low, a contaminated fill, a leaking filler seal or tank breather, and on older vehicles a corroded tank are the usual routes. A warning that returns quickly after draining is telling you the source is still there.
A fault in the sensor circuit can raise this warning with no water present, which is worth knowing and is not a reason to ignore it: draining costs nothing and settles the question immediately. If the bowl is dry and the lamp persists, then diagnose the sensor — and not before.
Working through it
| What you find | Likely cause | How to confirm it | What fixes it |
|---|---|---|---|
| Warning lit on a diesel, whatever else is happening | Water accumulated in the filter housing, at or near the level that would reach the injection pump | Open the drain on the filter bowl and catch what comes out. Water is visibly separate from diesel and settles below it. | Drain until clean fuel runs, then prime the system properly. Do this before driving further rather than at the next service. |
| Bowl drained and the warning returns within days | The source is still supplying water — contaminated fuel, a leaking filler seal or breather, or condensation from habitual low levels | Draw a tank sample and look at it. Check the filler seal and the tank breather, and ask about where the vehicle is fuelled. | Drain the tank if it is contaminated, renew the seal or breather, and keep the tank fuller in cold weather. |
| Bowl drains dry and the lamp stays on | The sensor or its circuit — a false warning | Read the sensor's live state with a known dry bowl. Inspect the connector, which sits low and collects moisture. | Renew the sensor or repair the connector. Only conclude this after draining, never instead of it. |
| Warning with rough running, power loss or hard starting | Water has already reached the injection system | Drain, then read injector correction values and rail pressure. Damage may already have occurred. | Do not keep running it. Assess the pump and injectors; water damage at rail pressures is rapid and expensive. |
| Large quantity of water drained at once | A contaminated fill rather than gradual condensation | The quantity is the evidence. Establish when and where the vehicle was last fuelled. | Drain the tank as well as the filter, renew the filter, and prime. Keep the receipt — this is sometimes recoverable from the supplier. |
-
Warning lit on a diesel, whatever else is happening
- Likely cause
- Water accumulated in the filter housing, at or near the level that would reach the injection pump
- How to confirm it
- Open the drain on the filter bowl and catch what comes out. Water is visibly separate from diesel and settles below it.
- What fixes it
- Drain until clean fuel runs, then prime the system properly. Do this before driving further rather than at the next service.
-
Bowl drained and the warning returns within days
- Likely cause
- The source is still supplying water — contaminated fuel, a leaking filler seal or breather, or condensation from habitual low levels
- How to confirm it
- Draw a tank sample and look at it. Check the filler seal and the tank breather, and ask about where the vehicle is fuelled.
- What fixes it
- Drain the tank if it is contaminated, renew the seal or breather, and keep the tank fuller in cold weather.
-
Bowl drains dry and the lamp stays on
- Likely cause
- The sensor or its circuit — a false warning
- How to confirm it
- Read the sensor's live state with a known dry bowl. Inspect the connector, which sits low and collects moisture.
- What fixes it
- Renew the sensor or repair the connector. Only conclude this after draining, never instead of it.
-
Warning with rough running, power loss or hard starting
- Likely cause
- Water has already reached the injection system
- How to confirm it
- Drain, then read injector correction values and rail pressure. Damage may already have occurred.
- What fixes it
- Do not keep running it. Assess the pump and injectors; water damage at rail pressures is rapid and expensive.
-
Large quantity of water drained at once
- Likely cause
- A contaminated fill rather than gradual condensation
- How to confirm it
- The quantity is the evidence. Establish when and where the vehicle was last fuelled.
- What fixes it
- Drain the tank as well as the filter, renew the filter, and prime. Keep the receipt — this is sometimes recoverable from the supplier.
Codes that produce this symptom (6)
Listed with the codes that most typically present this way first — the likeliest place to start.
- P2266 Water in Fuel Sensor A Circuit Low Typical of this code Moderate
- P2269 Water in Fuel Condition — Sensor A Typical of this code Stop driving High
- P2264 Water in Fuel Sensor A Circuit Moderate
- P2265 Water in Fuel Sensor A Circuit Range/Performance Moderate
- P2267 Water in Fuel Sensor A Circuit High Moderate
- P2268 Water in Fuel Sensor A Circuit Intermittent Moderate
Information, not instruction
CarGeek is a reference, not a service manual. Its pages are written from public sources and from what other people have found, never from a manufacturer's own service information, so they can be wrong or incomplete for your particular vehicle. Some of what they describe carries real risk: high voltage, fuel under pressure, stored energy, hot and moving parts.
Have anything you intend to act on checked by a trained person against the manufacturer's own procedure for your vehicle. Nothing here replaces that procedure.
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What makes one worth reading:
- The car — make, model, year and engine. The same fault behaves differently on each.
- What you measured, not only what you replaced.
- What actually fixed it — or that nothing did, which is worth knowing too.
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