P238E

Code

Generic P — Powertrain

Water in Fuel Sensor B Circuit Intermittent

Brand: Generic

Type: P — Powertrain

Views: UK: 26 EN: 41 RU: 26

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Corroded or loose connector at the water-in-fuel sensor B
Damaged wiring harness (short to ground, short to voltage, open circuit, or high resistance)
Contaminated or failed water-in-fuel sensor (internal corrosion or intermittent element)
Poor sensor ground or reference voltage from the engine control module (ECM)
Intermittent ECU input/output driver fault or intermittent software glitch
Water present in fuel or fuel filter/separator causing erratic sensor behavior

Malfunction Indicator Lamp (MIL) or Check Engine Light may come on intermittently
Stored/active P238E code(s), possibly intermittent or pending
Erratic or intermittent fuel-related drivability issues if water level fluctuates (hard starting, rough idle, hesitation)
Fuel system warning or water-in-fuel indicator (if equipped) may activate intermittently
No symptoms other than a fault code in some cases

Read freeze frame and occurrence count with a scan tool to see when the fault occurred
Check for related codes (other water-in-fuel sensor codes, fuel filter/separator codes, or circuit faults)
Visually inspect the sensor B connector and wiring for corrosion, bent pins, damage, or contamination
Inspect fuel filter/water separator area for signs of water or contamination
Backprobe sensor connector with a digital multimeter while monitoring live data or signal voltage
Perform a wiggle test on wiring/connectors while monitoring the signal to reproduce the fault

Typical sensor supply: switched or unswitched 5 V reference from ECM (approx. 5.0 V) — confirm with OEM data
Typical signal voltage when dry: stable logic/high (near reference voltage) or open-circuit depending on sensor design
Typical signal voltage when wet: pulled low or change state (near 0–1 V) for conductivity/switch-type sensors
Expected circuit resistance: open/infinite when dry for some switch types; low resistance (tens to a few hundred ohms) when immersed — check OEM spec
ECM input must have stable reference and ground (0 V ground), signal should not fluctuate rapidly when sensor state is constant

Retrieve full scan tool data: freeze frame, pending/confirmed status, and related codes.
Inspect sensor B connector and wiring for corrosion, water intrusion, damaged insulation, or pin damage. Repair or clean as needed.
With ignition ON (engine off), backprobe sensor connector: verify reference voltage and ground presence per OEM spec.
Monitor live data for the water-in-fuel B signal while operating or simulating wet/dry conditions (if safe) to confirm intermittent behavior.
Perform a wiggle test along the harness and at connectors while observing live data for signal drops or intermittent changes.
Measure continuity and resistance of the signal, power, and ground circuits from sensor B to the ECM; repair any open/high resistance or short circuits.
If wiring and connectors are OK, replace the water-in-fuel sensor B with a known-good part and retest.
If fault persists after sensor and wiring repair, inspect ECM connectors and grounds. Consider ECM input driver failure — consult OEM service information for ECM testing and possible reprogramming.
Clear codes and test drive to verify the fault does not return. Document intermittent occurrences and test conditions if still unresolved.