Blown fuse or corroded fuse contacts in the active grille shutter supply circuit; Damaged or chafed wiring between the body control module and the shutter B motor, often near the front bumper or grille opening; Loose or corroded electrical connector at the shutter B actuator, especially after front-end repairs or exposure to road splash; Failed active grille shutter B motor assembly with an internal open circuit on its power feed; Faulty body control module or power distribution module not supplying voltage to the shutter circuit; High resistance in a ground circuit shared by the shutter system, causing a voltage drop that mimics a low supply

DTC codes / P05xx · Vehicle speed, idle control and auxiliary inputs / P05B6

P05B6Active Grille Air Shutter B Supply Voltage Circuit Low

Q: What does code P05B6 mean?

Active Grille Air Shutter B Supply Voltage Circuit Low. P05B6 means the engine computer has detected that the supply voltage circuit for the active grille air shutter B motor is lower than expected, typically below a calibrated threshold. The active grille shutter system uses motorized vanes in the front grille to improve aerodynamics and fuel economy, and this code points to a power feed problem on the B shutter circuit rather than a mechanical jam.

P05B6 means the engine computer has detected that the supply voltage circuit for the active grille air shutter B motor is lower than expected, typically below a calibrated threshold. The active grille shutter system uses motorized vanes in the front grille to improve aerodynamics and fuel economy, and this code points to a power feed problem on the B shutter circuit rather than a mechanical jam.

SystemPowertrain

Code typeGeneric (all makes)

SeverityLow

Fix difficultyIntermediate

AreaVehicle speed, idle control and auxiliary inputs

Symptoms you may notice

Illumination of the check engine light, often with no other noticeable symptoms
The active grille shutters may remain stuck in the open position, reducing fuel economy at highway speeds
A faint whirring or clicking noise from the front grille area after shutdown if the shutter attempts to self-test and fails
Possible reduction in engine cooling efficiency if the shutters stay closed, though this is less common with a low-voltage supply fault
On some vehicles, a message in the driver information center about grille shutter service or aerodynamic performance

Common causes, most likely first

Blown fuse or corroded fuse contacts in the active grille shutter supply circuit
Damaged or chafed wiring between the body control module and the shutter B motor, often near the front bumper or grille opening
Loose or corroded electrical connector at the shutter B actuator, especially after front-end repairs or exposure to road splash
Failed active grille shutter B motor assembly with an internal open circuit on its power feed
Faulty body control module or power distribution module not supplying voltage to the shutter circuit
High resistance in a ground circuit shared by the shutter system, causing a voltage drop that mimics a low supply

How to diagnose and fix it

Inspect the active grille shutter fuse in the underhood fuse box and replace it if blown, then recheck for the code
Visually inspect the shutter B motor connector and wiring for corrosion, chafing, or loose pins, and clean or repair as needed
Use a digital multimeter to measure supply voltage at the shutter B motor connector with the key on, comparing it to battery voltage
Perform a voltage drop test on the supply circuit and ground circuit while the shutter is commanded to move, looking for excessive resistance
Command the active grille shutter with a scan tool to verify motor operation and check for mechanical binding that could overload the circuit
If voltage is low at the motor but present at the module, trace the circuit for an open or high-resistance fault and repair the harness
Replace the active grille shutter B motor assembly only after confirming the supply circuit and ground are intact and the module commands are correct

Why a low shutter supply voltage is often a wiring fault

A common oversight is replacing the shutter motor when the real problem is a corroded connector pin or a chafed wire behind the front bumper that only loses contact intermittently.
The code can set intermittently after a front-end repair or bumper replacement if the shutter harness was pinched or not properly routed during reassembly.
Some vehicles share the shutter supply circuit with other low-current actuators, so a fault elsewhere on that circuit can drag the voltage down and set P05B6 without any issue in the shutter itself.
A weak or failing battery or charging system can cause system voltage to sag during shutter self-tests, triggering a low supply code that disappears after the battery is replaced.
The active grille shutter may perform a self-test at every key-on cycle, so a low supply fault can set even when the vehicle has never been driven with the shutters commanded closed.

Can I keep driving with P05B6?

You can generally continue driving with P05B6 because the shutters default to a safe position and the engine will not overheat from this fault alone. Avoid ignoring repeated check engine lights, and have the circuit inspected soon to prevent a stuck shutter from affecting fuel economy or cooling.

Tools that help

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Guidance is general and written for all OBD-II vehicles. Exact tests and values vary by model, so confirm the fault before replacing parts.