P23CBFuel Rail Heater Control Circuit Low
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- How the car detects it
- P23CB means the control side of the fuel rail heater reads too low, normally a short to ground between the switching stage and the heating element. Since a rail heater draws a high current, a ground short on its feed can blow the fuse or trip the protection in the driving stage before the fuel gets warm. No manufacturer documents P23CB publicly. Bosch states that its Flexstart heating unit diagnoses shorts on each heating path and reports them to the engine module, which is how a code of this kind reaches the scan tool. CARB requires heated fuel preparation outputs to be monitored for circuit faults. In practice the engine still runs once warm, but cold starts on high ethanol content suffer. P23CA is the open and P23CC the high case.
- What you may notice
- Difficult cold start with ethanol
- Fuel heater fuse blows repeatedly
- Engine warning lamp, depending on manufacturer
- Likely causes
- LikelyHeater feed wire chafed to ground near the intake manifold
- PossibleHeating element shorted to the rail body
- PossibleFuel or water in the heater connector
- RareShorted output stage 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: €80 – €700
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.