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

P05B1 Active Grille Air Shutter B Control Circuit/Open

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. P05B1 concerns the control or motor coil circuit of actuator B. Ford's 3.0 L diesel reports an open and a shorted coil under it, checked at the start and 500 ms after each movement, fault after 10 s. Toyota's RAV4 Hybrid uses P05B1 as a collective code with failure types for short to positive, short to ground or open, and no signal. GM does not use it.

Likely causes

Actuator B coil open or shorted
Connector corroded or damaged (lower bumper, splash water)
Front harness damaged (impact, chafing, rodents)
Module

Symptoms

  • Check engine light on
  • Lower shutter inoperative
  • Slightly higher consumption, longer warm-up

Repair estimate

DifficultyMediumDIY possible
Parts and labour€80–450
Time0.5–2 h

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

Parts involved

grille shutter bgrille shutter actuator bactuator wiringengine control module

Related codes

P05A2P05B2P05B3P05B4U0285P05AE

References: fordservicecontent.com, vehicleservicepros.com, law.cornell.edu.