OBD-II code · Powertrain (generic, extended)
P23DE Cylinder 4 Fuel Heater Control Circuit High
Same as P23D2 on cylinder 4. 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 P23DE?
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 supply
- Less likelyConnector pins corroded - high contact resistance
- Less likelySupply wire pinched against B+ source
Repair at a glance
- Difficulty
- Medium
- DIY friendly
- Often, with basic tools
- Typical labour
- 0.5–1.8 h
- Emissions test
- Likely to fail
- Parts involved
- Fuel Heater Cyl 4
Related codes
- P23D2Cylinder 1 Fuel Heater Control Circuit High
- P23D6Cylinder 2 Fuel Heater Control Circuit High
- P23DACylinder 3 Fuel Heater Control Circuit High
- P23DBCylinder 3 Fuel Heater Control Circuit Low
- P23DCCylinder 3 Fuel Heater Performance
- P23DDCylinder 4 Fuel Heater Control Circuit Open
- P23DFCylinder 4 Fuel Heater Control Circuit Low
- P23E0Cylinder 4 Fuel Heater Performance
- P23E1EGR C Control Circuit Open
Code data: OBDex open dataset (CC0). Labour times are typical ranges, not a quote.