P2BF9Exhaust Flow Control Valve B Control Circuit Low
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- How the car detects it
- With P2BF9 the control line of exhaust flap B is pulled toward ground. A bare spot rubbing on the body or exhaust, or a shorted actuator, is the classic cause, which is why the code tends to appear after exhaust work or with a sagging harness. Ford's 2024 OBD summary treats it as subtype 11 of the bank 2 flap check, run continuously over 5 seconds by the smart driver. GM's 24OBDG07 tables describe a ground short on the exhaust valve PWM control circuit with battery voltage above 9 V, 4 seconds and a two-trip MIL. Ford bulletin 21-2011 for the 2020 Mustang GT500 lists P2BF9 among the active exhaust codes and points to pinched wiring at the actuator mount. Compared with P2BF8, the circuit is intact but shorted, so check insulation along the whole run rather than continuity alone.
- What you may notice
- Check engine light on
- Exhaust mode cannot be changed
- Bank 2 flap stuck, uneven sound left and right
- Likely causes
- LikelyControl wire chafed through and touching ground
- PossibleHarness pinched at the actuator bracket
- PossibleInternal short in the flap B actuator
- 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: €50 – €1,200
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.