P23CB: Fuel Rail Heater Control Circuit Low
Standardized SAE J2012 code · P23xx — Ignition system and misfire
What does P23CB mean?
Same as P23CA with the control line shorted to ground. Heated fuel rails and heaters at the individual injectors are used mainly on flex-fuel engines that may run on high-ethanol blends: ethanol vaporises poorly when cold, so the fuel is warmed before injection to allow a cold start without a separate gasoline starting tank. While the heater cannot be driven, cold starts on ethanol may be long or rough or fail altogether; once the engine is warm it runs normally.
The code tells you which monitor failed, not which part is broken. Test before replacing parts.
Symptoms
- Hard or failed cold start, especially on high-ethanol fuel
- Rough running right after a cold start
- Check engine light on
Common causes
- High Control line shorted to ground
- Low Connector pins corroded - high contact resistance
- Low Harness chafing through insulation
Likelihood is a general estimate across vehicles; your make and model may differ.
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