P23C7Fuel Heater Control Module Power Control Circuit/Open
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- How the car detects it
- Flex-fuel engines that must start on high-ethanol blends in the cold warm the fuel before injection, and a separate heating control unit switches the high heater currents on command of the engine module. P23C7 reports that the power control line to this unit is open or electrically faulty, so the heaters cannot be enabled. No manufacturer documents P23C7 publicly. Bosch describes its Flexstart heating control unit with a built-in relay for the heating current and full open/short diagnostics, and notes that ethanol ignites poorly below about 13 °C. CARB names heated fuel preparation systems as output components that need circuit monitoring. Expect long cranking or no start on ethanol in cold weather; P23C8 and P23C9 are the low and high cases.
- What you may notice
- Hard or failed cold starts on high ethanol blends
- Rough running right after a cold start
- Engine warning lamp, depending on manufacturer
- Likely causes
- LikelyBroken or disconnected power control wire between engine module and heater unit
- PossibleBlown fuse or failed relay feeding the heater control circuit
- PossibleCorroded or loose connector at the fuel heater control module
- RareInternal fault in the fuel heater 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.