Powertrain, generic (extended)

P2605 Intake Air Heater B Circuit/Open

Check engine lightOn
EmissionsRelevant
Drive cycleNot required
Limp modeNo

P2605 points to an open circuit at intake air heater B, a second heating element in the intake of a diesel engine; the control unit finds no current path through the element, its relay or the cabling. Volvo's EMS code lists keep heaters A, B and C apart. An August 2020 Volvo software change log for heavy-truck engines names P2605-13 among the codes tied to a preheater relay robustness problem, and a 2022 Volvo/Mack instruction for 11 L and 13 L engines asks for terminal tension checks at element and relay and a software check before relay and supply cable are renewed together. CARB expects intake air heater circuits to be watched for current and voltage drop. P0543 is the open-circuit code of heater A, P2CE1 that of heater C. Harder cold starts and white smoke follow.

Likely causes

Loose, corroded or burnt terminal at heater element or relay
Preheat relay no longer switching
Heater element B burnt through

Symptoms

  • Hard starting in cold weather
  • White smoke after a cold start
  • MIL on

Repair estimate

DifficultyMediumWorkshop job
Parts and labour€60–700
Time0.5–3 h

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

Parts involved

intake air heater bheater relaywiring harness

Related codes

P2606P2607P2608P2609P0543P2CE1

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