P23D0Fuel Heater Control Module Feedback Signal Circuit High
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- How the car detects it
- P23D0 applies when the return signal from the fuel heater control unit is stuck above its plausible maximum. A short to a voltage source on the feedback wire is the usual explanation; with a pull-up input in the engine module an open ground at the heater unit can produce the same picture. Because a pinned-high signal could be misread as an overheated heater, the engine module discards it and records a circuit fault instead. No manufacturer documents P23D0 publicly. Bosch's Flexstart unit is described as sending heat and diagnostic data back to the engine module, which is the signal checked here. CARB requires out-of-range detection on such monitored inputs. Fuel heating is usually switched off as a precaution. The low case is P23CF, implausible values P23CE.
- What you may notice
- Fuel heating switched off as a precaution
- Poor cold starts on high ethanol blends
- Engine warning lamp, depending on manufacturer
- Likely causes
- LikelyFeedback wire shorted to a voltage supply
- PossibleMissing ground at the fuel heater control module
- PossibleFeedback output of the heater unit stuck high
- RareFaulty input stage in the engine control module
- Inspection (ITP)
- Matters for the ITP. While the check-engine light is on, the car fails the emissions check.
- Repair
- Medium · Usually a job for a workshop.Typical cost: €50 – €600
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.