P23D3Cylinder 1 Fuel Heater Control Circuit Low
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- How the car detects it
- P23D3 reports that the control circuit of the cylinder 1 fuel heater is pulled toward ground. It follows the high code P23D2 in the numbering, not the other way round. A ground short on a heater path rated at a few hundred watts lets far too much current flow, so the heater unit or a fuse cuts the channel and cylinder 1 starts with cold fuel while the other heaters still work. Bosch states that its Flexstart unit detects shorts on its four heat circuits individually and reports them to the engine module. No manufacturer documents P23D3 publicly. CARB demands circuit checks on heated fuel preparation outputs. Expect a one-cylinder stumble on cold ethanol starts and possibly a blown fuse. Open circuit is P23D1, the other cylinders follow from P23D7.
- What you may notice
- Single-cylinder misfire on cold ethanol starts
- Blown fuse in the fuel heater circuit
- Engine warning lamp, depending on manufacturer
- Likely causes
- LikelyCylinder 1 heater wire chafed to ground on the intake or engine
- PossibleHeater at cylinder 1 shorted to its housing
- PossibleFuel or water in the cylinder 1 heater connector
- RareShorted channel 1 output in the heater unit
- 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.