What it means
Same as P059D on shutter B. Wiring faults of this kind typically come from chafing, water ingress at connector seals, or pin push-back — a wiggle test on the harness while the code is active often confirms the location.
At a glance
- Usually lights the check-engine light
How it works
The position sensor on active grille shutter B reports shutter movement to the control module so it can manage airflow through the grille. P05AC sets when the sensor signal circuit falls below its plausible range, commonly due to a short to ground, damaged wiring, or a poor connection.
Common causes
Most likely first.
- Signal shorted to ground
- Connector pins corroded - high contact resistance
- Harness chafing through insulation
Symptoms
- Check-engine light
- Shutter B may not move as commanded
- Cooling fan may run more often
How to diagnose it
- Review freeze-frame and live data to confirm the low signal and check whether shutter B's reported position changes when commanded.
- Inspect shutter B's sensor wiring and connector for chafing, exposed conductors, moisture, corrosion, or loose or pushed-back pins.
- With the code active, monitor the signal while gently moving the harness to check for changes.
- Test the position-sensor signal circuit for a short to ground or an open, using the vehicle's wiring information.
- If the circuit passes its checks, test shutter B's position sensor for an internal fault.
Common fixes
- Repair a signal wire shorted to ground.
- Clean and secure corroded or loose sensor connector terminals.
- Repair chafed wiring or a backed-out connector pin.
- Replace shutter B's position sensor if it fails testing with a sound circuit.
Can I keep driving?
A cautious drive is usually possible if engine temperature remains normal, though shutter B may not move as commanded and the fan may run more often. Monitor the temperature gauge and stop if the engine overheats.
A code shows where the control module detected a fault, not always which part failed. Check the causes in order and confirm with a test before replacing parts. Have several codes? Check them together
This is a generic code: it means the same on every make. The car’s maker may add more detail in its own service information.