Powertrain, generic (extended)

P2265 Water in Fuel Sensor A Circuit Range/Performance

Check engine lightUsually off
EmissionsNot relevant
Drive cycleNot required
Limp modeNo

P2265 means the signal from water-in-fuel sensor A is electrically present but does not behave plausibly, for example a self-test response that comes at the wrong time or a value that sits between the expected dry and wet states. No manufacturer documents P2265 publicly. A comparable check appears in GM's 2018 diesel tables under P2264: after a long ignition-off period the sensor has to signal water for a short moment right after power-up, and a missing response is judged as a fault. The probes measure conductivity between two electrodes in the water sump of the filter, so a film of dirt, biodiesel residue or a partly corroded probe can push the reading into an implausible zone. The code usually lights only a service or water warning; draining and cleaning come before replacing parts.

Likely causes

Sludge, emulsion or deposits coating the sensor electrodes
Sensor electronics drifting so the output lies between dry and wet
Corroded terminals adding resistance to the signal circuit

Symptoms

  • Water warning or service lamp that comes and goes
  • Water warning stays on even after the filter has been drained

Repair estimate

DifficultyEasyDIY possible
Parts and labour€20–200
Time0.3–1 h

Typical range across vehicles; the real cost depends on what the testing finds.

Parts involved

water in fuel sensorfuel filter housing

Related codes

P2264P2266P2267P2268P2269

References: gsi.ext.gm.com, patents.google.com, law.cornell.edu.