Powertrain, generic (extended)

P2BF6 Exhaust Flow Control Valve A Position Circuit Low

Check engine lightOn
EmissionsRelevant
Drive cycleNot required
Limp modePossible

P2BF6 means the position feedback of exhaust valve A sits below its valid range, as with a signal shorted to ground or a lost sensor supply. Mazda is the best documented user: its 2.5 litre Skyactiv-G with cylinder deactivation carries an exhaust shutter valve that Mazda patents describe as closing partly in two-cylinder mode to damp exhaust pulsation noise. Bulletin 01-004/20 calls P2BF6:00 a shutter valve position sensor low input detected within one drive cycle and reports the master warning light plus reduced power on 2019-2020 Mazda3 and 2020 CX-30; the cause was faulty PCM logic, cured by reprogramming. Mexican-market cars without deactivation are excluded. Deutz uses the same code on MD1 engines when the flap voltage drops under its normal band. Wiring and sensor must still be checked.

Likely causes

PCM software misjudging the sensor (Mazda bulletin 01-004/20)
Position signal wire shorted to ground
Sensor supply open or connector not latched
Position sensor in the shutter valve failed

Symptoms

  • Master warning or check engine light on
  • Reduced engine power

Repair estimate

DifficultyMediumWorkshop job
Parts and labour€0–900
Time0.5–2.5 h

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

Parts involved

exhaust flow control valve awiring harnessecm

Related codes

P2BF4P2BF5P2BF7P2BFEP26C6

References: static.nhtsa.gov, static.nhtsa.gov, patents.google.com, serdia.deutz.com.