P23D2Cylinder 1 Fuel Heater Control Circuit High
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- How the car detects it
- P23D2 is the high-voltage fault on the cylinder 1 heater circuit; note that in this series the high code comes before the low code (P23D3). The control side of the heater shows supply voltage while it should be switched off, so the switching stage has lost control: a short to a positive wire or a switching element that no longer turns off are the usual reasons. A heater left energized keeps warming fuel at cylinder 1 after start and draws current constantly. No manufacturer documents P23D2 publicly. Bosch credits its Flexstart heater unit with diagnosing the switching FETs of each of its four heat circuits, which is the kind of check behind this code. CARB requires circuit monitoring of heated fuel preparation. Opens are P23D1.
- What you may notice
- Cylinder 1 heater stays on, higher current draw
- Possible hot-restart problems
- Engine warning lamp, depending on manufacturer
- Likely causes
- LikelyCylinder 1 heater control wire shorted to a positive feed
- PossibleChannel 1 switching element stuck on in the heater unit
- RareDamaged connector letting the heater pin touch a supply pin
- Inspection (ITP)
- Matters for the ITP. While the check-engine light is on, the car fails the emissions check.
- Repair
- Medium · Usually a job for a workshop.Typical cost: €60 – €500
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.