P23D5
Cylinder 2 Fuel Heater Control Circuit Open
Per-cylinder fuel heaters (used on some heavy-duty diesels for cold-start atomisation) on cylinder 2 have an open control circuit.
- Check engine light: Yes
- Emissions related: Yes
- Repair difficulty: medium
Common causes
Ordered by how often each turns out to be the cause.
- Open in heater or wiringCommon
- Pin pushed back out of connector bodyLess likely
- Cracked solder joint inside the module or sensorLess likely
Parts involved
- Fuel Heater Cyl 2
P23D5 is a generic OBD-II code defined by SAE J2012. Exact wording and diagnostic procedure vary by manufacturer and model. Code definitions are drawn from the public-domain OBDex dataset; the workshop notes are our own.