Powertrain, generic (extended)

P2CBF PCV Heater B Control Circuit Low

Check engine lightOn
EmissionsRelevant
Drive cycleNot required
Limp modeNo

P2CBF is set when the control line of PCV heater B sits at ground potential at a moment the module expects a voltage on it. On the usual low-side layout, with supply fed directly to the heater and the module providing the ground, a short to ground on that line turns heater B on permanently regardless of command. The ventilation stays protected against frost, but the element draws current continuously and may age faster. No manufacturer documents P2CBF publicly; the A-side code P053B is checked by GM's 2016 diesels at coolant below 90 °C with 20 of 40 failing samples, Type C without lamp. A pinched harness against the engine block or a damaged connector is the typical find.

Likely causes

Control wire pinched or chafed to engine ground
Damaged connector at heater B
Output stage in the engine module shorted internally

Symptoms

  • Code stored, MIL depending on manufacturer
  • Heater B constantly on, slightly higher electrical load
  • Usually no driveability complaint

Repair estimate

DifficultyMediumDIY possible
Parts and labour€20–200
Time0.5–2 h

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

Parts involved

pcv heater bwiring harnessecm

Related codes

P2CBDP2CBEP2CC0P053B

References: gsi.ext.gm.com, saabwisonline.com, law.cornell.edu.