P23C8Fuel Heater Control Module Power Control Circuit Low
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- How the car detects it
- P23C8 covers the case where the engine module finds the heater unit's power control line pulled to ground. The likely culprit is a chafed wire touching the body or engine, or a short inside the heater unit. Because the line is held low, the heating unit either never receives its enable or, depending on the circuit design, the fuse protecting it may blow. No manufacturer documents P23C8 publicly; the background is Bosch's Flexstart concept, in which the heating control unit drives the fuel heaters with roughly 260 W per circuit at 12 V and reports short-circuit diagnostics back. CARB requires circuit checks on heated fuel preparation. The car usually still runs on gasoline-rich fuel; cold starts with ethanol become difficult. Open is P23C7, high P23C9.
- What you may notice
- Long cranking in cold weather on ethanol
- Blown fuse in the fuel heater circuit
- Engine warning lamp, depending on manufacturer
- Likely causes
- LikelyPower control wire chafed through to ground
- PossibleMoisture in the heater unit connector creating a path to ground
- PossibleShorted control input inside the fuel heater control module
- RareFaulty output driver 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.