OBD-II code · Powertrain (generic, extended)
P23CB Fuel Rail Heater Control Circuit Low
Same as P23CA with the control line shorted to ground. The sensor heater warms the element to operating temperature (~600 °C); without it the lambda sensor stays inactive in closed loop and the ECM cannot trim mixture.
Is it safe to drive with P23CB?
Usually safe to drive in the short term. Get it diagnosed when convenient, sooner if the car drives differently.
Common causes
- Most likelyControl line shorted to ground
- Less likelyConnector pins corroded - high contact resistance
- Less likelyHarness chafing through insulation
Repair at a glance
- Difficulty
- Medium
- DIY friendly
- Often, with basic tools
- Typical labour
- 0.6–2 h
- Emissions test
- Likely to fail
- Parts involved
- Fuel Rail Heater
Related codes
- P23C8Fuel Heater Control Module Power Control Circuit Low
- P23C9Fuel Heater Control Module Power Control Circuit High
- P23CAFuel Rail Heater Control Circuit Open
- P23CCFuel Rail Heater Control Circuit High
- P23CDFuel Heater Control Module Feedback Signal Open
- P23CEFuel Heater Control Module Feedback Signal Performance
Code data: OBDex open dataset (CC0). Labour times are typical ranges, not a quote.