P05B4Active Grille Air Shutter B Control Circuit Low
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- Needs a drive cycle to confirm a fix
- How the car detects it
- 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.
- What you may notice
- Check engine light on
- Lower shutter inoperative
- Slightly higher consumption, longer warm-up
- Likely causes
- LikelyActuator B faulty internally
- PossibleControl line shorted to ground (chafing, impact)
- PossibleCorroded connector
- RareModule
- Inspection (ITP)
- Matters for the ITP. While the check-engine light is on, the car fails the emissions check.
- Repair
- Medium · Often possible to do yourself.Typical cost: €80 – €450
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.