Powertrain, generic (extended)

P2D12 Exhaust Flow Control Valve B Position Not Learned

Check engine lightOn
EmissionsRelevant
Drive cycleNot required
Limp modeNo

P2D12 is the counterpart of P2D11 for the second flap or bank 2: the stored end positions of exhaust valve B are missing or were rejected. No manufacturer documents P2D12 publicly. The closest public logic sits in GM's 23OBDG07 table, which decides from the PWM feedback of exhaust valve 2 whether its end stops have been learned, over 4 seconds with more than 9 V on board, as a two-trip fault under its own code P3181. Ford needs the same alignment on the 2023-2025 F-150 with supercharged 5.2 L V8 (bulletin 25-2144) if the B monitor status PID shows 3, yet stores P2BF8 subtype 78 or P2BFB for it. GM bulletin PIC6289C warns that a disconnected battery can force a relearn. A scan tool learn run usually cures it; if it fails again, the flap or its mounting binds.

Likely causes

Alignment or learn run for valve B skipped after repair
Adaptation erased by a discharged or disconnected battery
Actuator mounted out of position or flap shaft binding
Outdated engine software that makes the learn fail

Symptoms

  • MIL on, sometimes with an exhaust mode not available message
  • Flap B noisy or searching for position
  • No audible change between sound modes on one side

Repair estimate

DifficultyMediumWorkshop job
Parts and labour€0–600
Time0.3–1.5 h

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

Parts involved

exhaust flow control valve becm

Related codes

P2D11P2D1BP2BF8P2BFBP2BFD

References: gsi.ext.gm.com, static.nhtsa.gov, static.nhtsa.gov, law.cornell.edu.