P23D5Cylinder 2 Fuel Heater Control Circuit/Open
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- How the car detects it
- Cylinder 2 has its own fuel heating path on flex-fuel engines that warm the fuel per cylinder, and P23D5 says this path carries no current although the heater is commanded on, or the control line shows a general fault. To the heater unit the open simply looks like a missing load on channel 2. Bosch describes its Flexstart unit as checking each of four heat circuits for interruption and shorts and passing the result to the engine controller. No carmaker publishes P23D5 or its limits. CARB lists heated fuel preparation among the output systems to be monitored. Cylinder 2 then receives cold ethanol during the first seconds of a cold start. A quick check is to compare the resistance of heater 2 with that of its neighbours. Shorts on the same path are P23D6 and P23D7.
- What you may notice
- Cylinder 2 misfires briefly after a cold start on ethanol
- Uneven idle in the first minute when cold
- Engine warning lamp, depending on manufacturer
- Likely causes
- LikelyHeater at cylinder 2 burnt through (open element)
- PossibleCylinder 2 heater plug loose or not latched after intake work
- PossibleBroken conductor in the cylinder 2 heater lead
- RareChannel 2 output of the heater control unit failed
- 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.