P05B5

What it means

P05B5 is a generic powertrain code meaning the control unit has detected a fault in the supply voltage circuit, or an open circuit, for active grille air shutter 'B'. The module that drives the shutters expects a correct supply voltage and sees none, too little, or a broken feed. Which shutter set is 'B' and how the system is wired depends on the vehicle, so check the manufacturer's information.

Symptoms

• Engine warning light on
• Active grille shutters stuck open or stuck closed
• Slightly higher fuel consumption at motorway speeds
• Engine or transmission running hotter than usual in traffic if the shutters stay closed
• Air conditioning performing poorly at idle if the shutters stay closed
• Other stored faults for the shutter actuator or its communication

Possible causes

• Damaged, corroded or loose connector at the active grille shutter actuator, often because of its exposed position behind the bumperlikely
• Open circuit or chafed wiring in the supply feed to the shutter actuatorlikely
• Blown fuse or faulty relay supplying the shutter actuator circuitpossible
• Internal fault in the shutter actuator or motor pulling the supply downpossible
• Poor earth connection or low system voltage from a weak battery or charging faultpossible
• Fault inside the engine control unit or the module driving the shuttersrare

How to diagnose

1. Read all stored codes and freeze frame data, and note any battery voltage, communication or shutter actuator codes
2. Check the battery condition and charging voltage, as low voltage can set supply circuit faults
3. Visually inspect the shutter assembly, actuator, wiring and connector for impact damage, debris, corrosion or water ingress
4. Check the relevant fuse and relay against the vehicle wiring diagram
5. Operate the shutters using a scan tool actuator test if the vehicle supports it, and see whether they move and are free of obstruction
6. With the connector unplugged, test for supply voltage and a good earth at the actuator connector as per the wiring diagram
7. Test the supply wiring for continuity and shorts to earth back to the control unit
8. Clear the code after repair and road test to confirm it does not return

How to fix

• Clean, repair or replace the damaged connector or terminals at the shutter actuator
• Repair or replace the open or chafed wiring in the supply circuit
• Replace the blown fuse after finding out why it failed, or replace a faulty relay
• Replace the shutter actuator or shutter assembly if it is faulty or mechanically seized
• Correct the battery or charging system fault and repair any poor earth connection
• Replace or reprogram the control module only after the wiring and actuator have been proven good and the manufacturer confirms it

Can I keep driving?

Nearby codes

• P05B4GenericActive Grille Air Shutter B Control Circuit Low
• P05B6GenericActive Grille Air Shutter B Supply Voltage Circuit Low