P2D12Exhaust Flow Control Valve B Position Not Learned
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- How the car detects it
- 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.
- What you may notice
- 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
- Likely causes
- LikelyAlignment or learn run for valve B skipped after repair
- PossibleAdaptation erased by a discharged or disconnected battery
- PossibleActuator mounted out of position or flap shaft binding
- RareOutdated engine software that makes the learn fail
- Inspection (ITP)
- Matters for the ITP. While the check-engine light is on, the car fails the emissions check.
- Repair
- Medium · Usually a job for a workshop.Typical cost: €0 – €600
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.