Powertrain, generic (extended)

P23DC Cylinder 3 Fuel Heater Performance

Check engine lightOn
EmissionsRelevant
Drive cycleRequired
Limp modeNo

P23DC is set when the heating at cylinder 3 works electrically but delivers too little effect. Bosch writes that its heater unit follows the heat output of all four circuits and hands a temperature reading to the engine controller, so a channel that warms more weakly than the others can be singled out. Such systems exist because ethanol-rich fuel is hard to ignite in the cold: Brazilian flex cars long carried a small petrol tank for cold starts, and the 2009 VW Polo E-Flex was the first model to do without it. If cylinder 3 stays underheated, it misfires or runs lean during warm-up. Weak elements, deposits or a high-resistance joint are typical. No manufacturer documents P23DC or its limits; CARB asks for functional monitoring.

Likely causes

Cylinder 3 heating element below its rated output
High-resistance crimp or plug in the cylinder 3 heater circuit
Deposits insulating the heated surface

Symptoms

  • Misfire on cylinder 3 during warm-up on ethanol
  • Lean running in the first minutes
  • Engine warning lamp, depending on manufacturer

Repair estimate

DifficultyHardWorkshop job
Parts and labour€80–600
Time1–3 h

Typical range across vehicles; the real cost depends on what the testing finds.

Parts involved

fuel heater cyl 3

Related codes

P23D9P23DAP23DBP23D8P23E0

References: bosch-mobility.com, en.wikipedia.org, law.cornell.edu.