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

P05B4 Active Grille Air Shutter B Control 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. P05B4 means the control circuit voltage of actuator B is too low – typically the control line shorted to ground; the actuator cannot be driven. No manufacturer document available to us uses this code, like its shutter A counterpart. Toyota reports a short to ground or open circuit as P05B1 with failure type 14.

Likely causes

Actuator B faulty internally
Control line shorted to ground (chafing, impact)
Corroded connector
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

P05B3P05B1P05B2P05B6P05A5

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