Open circuit, high resistance or short to ground in the shutter actuator supply wiring; Corroded, loose or damaged connector at the shutter actuator or control unit; Blown fuse or faulty relay feeding the shutter actuator supply; Faulty shutter actuator or motor drawing excessive current and pulling the supply down; Seized or damaged shutter vanes or linkage overloading the actuator; Low system voltage from a weak battery or charging fault; Fault inside the control unit driving the supply circuit.

P05B6

Active Grille Air Shutter B Supply Voltage Circuit Low.

Generic
Powertrain
Generic code
Low severity

How this code is built

P: SystemPowertrain
0: Defined bySAE, the same on every car
5: AreaVehicle speed, idle control and auxiliary inputs
B6: FaultThe specific fault in that area

What it means

P05B6 means the control unit has detected a low voltage on the supply circuit for active grille air shutter 'B'. The active grille shutters open and close to balance engine cooling against aerodynamic drag. The module monitors the supply voltage to the shutter actuator and sets the code when it reads below the expected range. The number and layout of shutter circuits varies by model, so check which circuit 'B' refers to on the vehicle in question.

Symptoms

Engine warning light on
Active grille shutters stuck open or stuck closed
Shutters not moving when the engine is warm or cold
Slightly higher fuel consumption at motorway speeds
Engine or transmission running hotter than usual in heavy load or hot weather
Rattling or buzzing noise from the front grille area

Possible causes

Open circuit, high resistance or short to ground in the shutter actuator supply wiringlikely
Corroded, loose or damaged connector at the shutter actuator or control unitlikely
Blown fuse or faulty relay feeding the shutter actuator supplylikely
Faulty shutter actuator or motor drawing excessive current and pulling the supply downpossible
Seized or damaged shutter vanes or linkage overloading the actuatorpossible
Low system voltage from a weak battery or charging faultpossible
Fault inside the control unit driving the supply circuitrare

How to diagnose

Read all stored codes and freeze frame data, noting battery voltage, engine temperature and vehicle speed when the fault set, and look for other voltage or charging codes
Check battery condition and charging voltage to rule out a general low-voltage problem
Visually inspect the grille shutters for debris, damage, ice or obstruction and move the vanes by hand (if safe to do so) to check for binding
Inspect the actuator wiring and connectors for chafing, water ingress, corrosion and pushed-back pins, especially at the front of the car where damage from impact or road spray is common
Check the relevant fuse and relay against the wiring diagram for the model
Measure the supply voltage and ground at the actuator connector with the circuit active, and test for voltage drop under load
Use a bidirectional scan function, if available, to command the shutters and watch the response
Check the wiring for continuity and shorts to ground between the actuator and the control unit, following the manufacturer's wiring diagram

How to fix

Repair or replace damaged wiring and renew any corroded or damaged connector terminals
Replace the blown fuse or faulty relay after finding out why it failed
Free or replace seized shutter vanes and linkage
Replace the shutter actuator if it has an internal fault or draws excess current
Restore proper battery and charging system condition if system voltage is low
Repair or replace the control unit only after the wiring and actuator have been proven good, following the manufacturer's procedure

Can I keep driving?

Low severity

The car can normally be driven, but book it in soon. If the shutters are stuck closed, watch the temperature gauge in hot weather or under heavy load and stop if the engine overheats.

Guide written by AI from the code's definition. Confirm with a diagnosis before replacing parts.