Powertrain, generic · Vehicle speed, idle control and auxiliary inputs

P05B6 Active Grille Air Shutter B Supply Voltage Circuit Low

Check engine lightOn
EmissionsRelevant
Drive cycleRequired
Limp modeNo

Shutter B is the second active grille shutter – at GM, Ford and Stellantis the lower one in the bumper. Shutters cut drag and speed warm-up when closed and open for cooling; CARB names them as an off-cycle CO2 technology and treats the actuator as an output component. Smart actuators report over LIN (loss of communication: U0285); a fault usually costs fuel and warm-up time, a closed shutter can make the engine run hot under load. P05B6 means the supply of actuator B is present but too low. Ford's 3.0 L diesel sets it at once when the actuator measures its internal supply below 6.9 V while system voltage is 9–16.26 V, from 5 s after start – pointing to a voltage drop in feed or ground or an internal fault.

Likely causes

Contact resistance in connector, wire or ground (corrosion)
Actuator faulty internally (measuring wrong)
Weak battery or charging system

Symptoms

  • Check engine light on
  • Lower shutter inoperative at times
  • Possibly further voltage codes or U0285

Repair estimate

DifficultyEasyDIY possible
Parts and labour€20–400
Time0.3–2 h

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

Parts involved

grille shutter actuator bactuator power supplyactuator wiring

Related codes

P05B5P05B7P0562U0285P05A7

References: fordservicecontent.com, static.nhtsa.gov, law.cornell.edu.