Code
P1140
Other
P — Powertrain
Water In Fuel Condition
Views:
UK: 27
EN: 53
RU: 36
AI status
Completed
Completed
100%
Causes
- Water contamination in fuel (rain, tank condensation, poor fuel quality, or contaminated fill-up).
- Saturated or damaged fuel filter / water separator.
- Failed or sticking water-in-fuel sensor or float switch.
- Corroded, damaged, or open/shorted sensor wiring or connectors.
- Faulty fuel tank/water sensor ground or module input circuit.
- Incorrect PCM/ECM software or false trigger from other fuel system faults.
Symptoms
- Check Engine Light (MIL) illuminated with DTC P1140.
- Hard starting or extended cranking, especially after sitting.
- Rough idle, stalling, or intermittent power loss.
- Reduced engine performance or limp mode on some vehicles.
- Fuel odor or visible water/fuel separation in drain bowl.
- Fuel filter/water separator drain contains water or murky fluid.
What to check
- Scan for P1140 and any related DTCs; record freeze frame and live data.
- Visually inspect fuel filter/water separator drain bowl for water; safely drain per manufacturer procedure.
- Inspect wiring and connector at water-in-fuel sensor for corrosion, bent pins, or water ingress.
- Check sensor harness for continuity, shorts to ground, and proper reference voltage using wiring diagram.
- Smell/test suspect fuel sample for water or contamination (use proper test kit or allow lab testing).
- Confirm fuel filter change/service history and check for service interval overdue.
Signal parameters
- Water-in-fuel sensor output voltage or resistance (vehicle-specific): typical float/switch outputs may read near 0–1 V or closed circuit when water present and ~4–5 V or open when dry — consult OEM spec.
- Reference supply (5 V or ignition-switched) to sensor — should be present with ignition on per wiring diagram.
- Signal circuit continuity to PCM/ECM: near zero ohms to connector, open/infinite if broken.
- Scan-tool live data: water-in-fuel status bit (0/1) or percent contamination if applicable.
- Fuel pressure and delivery parameters to rule out unrelated fuel system faults.
Diagnostic algorithm
- Safety first: work in well-ventilated area, no open flames; relieve fuel system pressure per procedure.
- Read and record all stored codes and freeze frame data; clear codes and perform a drive cycle to see if P1140 returns.
- Inspect and drain the fuel filter/water separator drain bowl into an appropriate container and look for water layer or discoloration; note quantity.
- If water present, replace fuel filter/water separator and drain the separator per service procedure; retest and clear codes.
- Visually inspect the water-in-fuel sensor and its connector; disconnect, clean terminals, and reconnect. Replace sensor if corroded or mechanically damaged.
- Backprobe sensor with a scan tool or multimeter to check reference voltage, ground, and signal while activating sensor (if manual drain/float activation possible) — compare to OEM values.
- If wiring faults suspected, perform pin-to-pin continuity and resistance checks between sensor connector and PCM; repair any damaged wiring or connectors.
- If no water found and sensor/electrical checks are good, inspect fuel tank for contamination (siphon a small sample) and consider lab testing. Replace contaminated fuel and clean tank if required.
- After repairs, clear codes and perform functional test/drive cycle to confirm fault does not return; document findings and replaced parts.
Likely causes
- Clogged/wet fuel filter or water separator requiring drain/replacement.
- Failed water-in-fuel sensor (electrical or mechanical failure).
- Connector corrosion or intermittent wiring to sensor.
- Actual water in fuel tank due to contaminated fueling or condensation.
Fault status
Status
Water detected in fuel system (water-in-fuel sensor triggered). MIL on; possible reduced performance or limp mode. Service fuel filter/water separator and inspect sensor/wiring.
Repair difficulty: Medium
Diagnostic time: 0.5-2.0 hours
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