Powertrain, generic (extended)

P223B Reductant Heater F Control Circuit

Check engine lightOn
EmissionsRelevant
Drive cycleNot required
Limp modePossible

P223B reports a fault in the control circuit of heater F, the sixth heating element of an SCR system. Like its neighbour P223A for heater E, it is a single catch-all code covering open lines and shorts alike. No maker documents P223B publicly, and the published systems show why: Ford's 2023 diesel summary names heaters A to C only (with A and B checked at peak heating power for under 3 A at more than 5 V), and GM bulletin 21-NA-149 lists the heater D codes P20C5 and P20C8 for the 3.0 L LM2 Duramax. Six zones would only appear on layouts with many separately heated lines or tanks. CARB requires every emission-relevant output to be checked for circuit faults. Expect an SCR warning and, in winter, the risk of a frozen line that ends in reduced power.

Likely causes

Damaged wiring or corroded connector of heater F
Heating element F open or shorted
Missing supply from the heater relay or fuse

Symptoms

  • Check engine light and SCR warning
  • Reduced power warning after a cold-weather DEF fault

Repair estimate

DifficultyHardWorkshop job
Parts and labour€100–1,200
Time1–4 h

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

Parts involved

reductant line heater f

Related codes

P223AP20C5P20C1P21C2

References: law.cornell.edu, fordservicecontent.com, static.nhtsa.gov.