P226A

Code

Generic P — Powertrain

Water in Fuel Lamp Control Circuit

Brand: Generic

Type: P — Powertrain

Views: UK: 21 EN: 48 RU: 30

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Page language: EN

Causes

Open or short in the water-in-fuel lamp/control wiring
Corroded or damaged connector at the sensor, lamp or module
Failed water-in-fuel sensor or level switch in the fuel filter
Failed lamp or instrument cluster lamp driver
Blown fuse or poor ground
Aftermarket or improperly installed filter/sensor

Symptoms

'Water in Fuel' lamp illuminates incorrectly or not at all
Lamp stays on continuously or blinks intermittently
Related message in the instrument cluster (e.g., 'Water in Fuel')
No drivability issues unless fuel contaminated (code relates to indicator circuit only)
Possible stored related electrical/circuit codes

What to check

Read freeze frame and any related codes with a scan tool
Visually inspect the fuel filter area and sensor connector for corrosion or water
Check fuse(s) and ground(s) for the lamp/control circuit
Backprobe the sensor/lamp connector to observe signal with key ON
Wiggle test wiring while monitoring lamp status or live data for intermittency

Signal parameters

Circuit type: typically a switched/grounded sensor or a low-voltage signal to lamp driver
Expected reference: usually 0–5 V signal or a simple open/closed switch to ground
When dry: sensor output = open or 'normal' voltage; when water present: output changes state (low/high depending on design)
Fault present: open circuit, short to power, short to ground, or intermittent/high resistance

Diagnostic algorithm

Retrieve freeze frame and related DTCs. Note whether lamp is commanded ON by the module.
Visually inspect wiring, connector(s) and the fuel filter/water sensor for damage, corrosion or improper installation.
Verify fuses and instrument cluster lamp operation (activate lamp via scan tool or command if available).
With key ON (engine OFF), backprobe the sensor connector and measure signal/reference voltage. Compare to expected behavior (change when sensor is wet/dry if possible).
Check continuity from the sensor/lamp connector to the module and to ground; look for shorts to battery voltage or ground.
If wiring and connectors are good, bench-test or replace the water-in-fuel sensor/switch, then clear codes and retest.
If fault persists after replacing sensor and repairing wiring, test or replace the instrument cluster lamp driver or investigate module outputs; consider module replacement only after other causes are eliminated.
After repairs, clear codes and perform a functional test (wet the sensor or use a known-good sensor) to confirm lamp and circuit operation.

Likely causes

Corroded connector at the water-in-fuel sensor or lamp
Failed water-in-fuel switch inside fuel filter
Broken or chafed harness causing open or short to power/ground
Blown/loose fuse protecting the lamp circuit
Faulty lamp driver in the instrument cluster or control module

Fault status

⚠️ Status

Water in Fuel Lamp Control Circuit fault detected — electrical malfunction (open/short/high resistance/intermittent) in the water-in-fuel indicator circuit. Inspect sensor, connectors, wiring, fuses and lamp driver.

🟡 Repair difficulty: Medium

⏱️ Diagnostic time: 0.5-2.0 hours