OBD-II code · Powertrain (generic, extended)
P23DD Cylinder 4 Fuel Heater Control Circuit Open
Per-cylinder fuel heaters (used on some heavy-duty diesels for cold-start atomisation) on cylinder 4 have an open control circuit.
Is it safe to drive with P23DD?
Usually safe to drive in the short term. Get it diagnosed when convenient, sooner if the car drives differently.
Common causes
- Most likelyOpen in heater or wiring
- Less likelyPin pushed back out of connector body
- Less likelyCracked solder joint inside the module or sensor
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
- P23D1Cylinder 1 Fuel Heater Control Circuit Open
- P23D5Cylinder 2 Fuel Heater Control Circuit Open
- P23D9Cylinder 3 Fuel Heater Control Circuit Open
- P23DACylinder 3 Fuel Heater Control Circuit High
- P23DBCylinder 3 Fuel Heater Control Circuit Low
- P23DCCylinder 3 Fuel Heater Performance
- P23DECylinder 4 Fuel Heater Control Circuit High
- P23DFCylinder 4 Fuel Heater Control Circuit Low
- P23E0Cylinder 4 Fuel Heater Performance
Code data: OBDex open dataset (CC0). Labour times are typical ranges, not a quote.