Powertrain, generic (extended)

P23E0 Cylinder 4 Fuel Heater Performance

Check engine lightOn
EmissionsRelevant
Drive cycleRequired
Limp modeNo

P23E0 judges the effect of the cylinder 4 heater rather than its wiring: the circuit is intact, but the heat delivered or the temperature reached falls short of what the conditions call for. One factor specific to resistive heaters is supply voltage. Bosch specifies 260 W per heating element at 12 V; since power falls with the square of voltage, a weak battery at 10 V during cranking leaves only about 180 W, and warm-up takes noticeably longer. A performance code on one cylinder alone, however, points to that heater: an aged element, deposits or a poor contact. The engine control sets the heating demand from ethanol content and outside temperature, so the fault shows mainly in cold weather on high-ethanol fuel. No manufacturer documents P23E0; CARB expects functional monitoring.

Likely causes

Aged heater at cylinder 4 with reduced output
Poor contact in the cylinder 4 heater circuit
Weak battery or low system voltage during heating

Symptoms

  • Rough start in cold weather on high-ethanol fuel
  • Longer cranking
  • 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 4

Related codes

P23DDP23DEP23DFP23DCP23D4

References: bosch-mobility.com, bosch-mobility.com, law.cornell.edu.