Powertrain, generic (extended)

P2BFF Exhaust Flow Control Valve B Position Circuit High

Check engine lightOn
EmissionsRelevant
Drive cycleNot required
Limp modeNo

P2BFF is the upper limit fault for the position feedback of exhaust flap B. An analog signal pinned near supply voltage, or a PWM feedback stuck near 100 percent, usually comes from a lost sensor ground, a signal wire touching voltage, or water bridging the connector pins. No manufacturer documents P2BFF publicly. Deutz uses the valve A counterpart P2BF7 when its flap voltage is too high, and GM's 23OBDG07 tables fail the second exhaust valve feedback above 98 percent duty cycle after 4 seconds, two trips to the MIL, under a GM-specific code. CARB asks for range checks on inputs of this kind. Unlike P2BFA, which concerns the drive line, this code points at the return signal, so the flap may still move while the computer no longer trusts the reported angle.

Likely causes

Open ground at the flap B position sensor
Water or salt bridging the actuator B connector pins
Signal wire shorted to a voltage source

Symptoms

  • Check engine light on
  • Exhaust mode warning, flap B held in default position

Repair estimate

DifficultyMediumWorkshop job
Parts and labour€50–900
Time0.5–2.5 h

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

Parts involved

exhaust flow control valve bwiring harnessecm

Related codes

P2BFCP2BFDP2BFEP2BF7P2BFA

References: law.cornell.edu, serdia.deutz.com, gsi.ext.gm.com.