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. P05B5 means the battery supply of actuator B via fuse or relay is missing or open; without it there is no movement, and smart actuators drop off the LIN bus. No manufacturer document available to us uses this code, like its shutter A counterpart. VW's check measures supply and ground at the actuator connector; GM feeds its actuators via a relay but uses other codes.
Medium severity. Can I keep driving?If the car is running normally, drive in moderation to a repair shop. If it loses power or another warning appears, do not continue.
Symptoms
- Check engine light on
- Lower shutter inoperative
- Possibly also U0285
Most likely causes
- Fuse blown or relay faulty
- Broken wire or connector off in the lower front end
- Ground connection open
- Actuator faulty internally
What to check, in order
Start with the simplest. You can tick off each step.
Good to know
- Repair difficulty: easy
- It affects emissions.
What each character of P05B5 means
- P: Powertrain: engine and transmission
- 0: Generic code: same on every make
- 5: Speed and idle
- B5: Specific fault in that system
Frequently asked questions
Can I keep driving with code P05B5?
If the car is running normally, drive in moderation to a repair shop. If it loses power or another warning appears, do not continue.
What causes code P05B5?
The most common causes are: fuse blown or relay faulty; broken wire or connector off in the lower front end; ground connection open.
Related codes
- P05B6Active Grille Air Shutter B Supply Voltage Circuit Low
- P05B7Active Grille Air Shutter B Supply Voltage Circuit High
- P05B1Active Grille Air Shutter B Control Circuit/Open
- U0285Lost Communication With Active Grille Air Shutter Module B
- P05A6Active Grille Air Shutter A Supply Voltage Circuit/Open
Sources
- law.cornell.edu: 13 CCR 1968.2
- static.nhtsa.gov: MC 10194520 0001
- gsi.ext.gm.com: 19OBDG03B Diagnostics
Values and procedures vary by manufacturer. If it affects brakes, steering, fuel or high voltage, see a professional. Updated: 2026-11-04. How we build these pages.