Powertrain, generic (extended)

P2CE4 Intake Air Heater C Circuit High

Check engine lightOn
EmissionsRelevant
Drive cycleNot required
Limp modeNo

P2CE4 is stored when heater C's circuit shows an excessive signal, typically a short to battery voltage on the control line or a relay that remains switched on. Volvo and Mack document it as P2CE4-12, the suffix standing for a short to battery. It appears in their pre-heat relay instructions for Volvo VN/VNL/VNR/VNX/VHD and Mack Anthem, Granite, Pinnacle and other models from 2014, where technicians first check terminal tension at element and relay and the EMS software, then fit a new relay, supply cable and an updated two-point bracket (2022 version). A heater stuck on can flatten the batteries and overheat the cable, so this fault deserves quick attention. P2CE3 is the low-side code, P2CE1 the open circuit; heater A and B use P0542 and P2608.

Likely causes

Pre-heat relay contacts welded or stuck closed
Control line of heater C shorted to a battery-voltage wire
Faulty supply power cable or loose bracket mounting affecting the circuit
Engine control module output stage for the relay faulty

Symptoms

  • Batteries drained after the truck has been parked
  • Hot or discoloured cable near the heater
  • Warning lamp and possibly hard starting if the heater no longer switches

Repair estimate

DifficultyMediumWorkshop job
Parts and labour€80–900
Time0.5–3 h

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

Parts involved

intake air heater cheater relaywiring harnessecm

Related codes

P2CE1P2CE2P2CE3P0542P2608

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