Powertrain, generic (extended)

P23CE Fuel Heater Control Module Feedback Signal Performance

Check engine lightOn
EmissionsRelevant
Drive cycleRequired
Limp modeNo

Unlike the open and short codes, P23CE concerns a feedback signal that is electrically present but does not fit what the engine module expects. The heater unit may, for example, report no temperature rise during a commanded heating phase, a rise that is far too slow, or values that contradict the command state. Bosch's Flexstart heater unit measures the heat it delivers and passes it on, so a weak heating element, poor contact on a high-current path or a drifting measurement can all surface here. No manufacturer documents P23CE or its thresholds publicly. CARB asks for functional checks on heated fuel preparation, not only circuit checks. Cold starts on ethanol may be slow even though no wire is broken; a missing signal is P23CD.

Likely causes

Aged heating element delivering less heat than commanded
High resistance at heater power or ground terminals
Drifting temperature or current measurement inside the heater unit
Weak battery reducing heating power during cranking

Symptoms

  • Slow or rough cold starts on ethanol without a wiring fault
  • Engine warning lamp, depending on manufacturer

Repair estimate

DifficultyHardWorkshop job
Parts and labour€80–800
Time1–3 h

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

Parts involved

fuel heater control module

Related codes

P23CDP23CFP23D0P23D4

References: bosch-mobility.com, law.cornell.edu.