What it means
Active air dam actuator control voltage above expected range. 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 ABS or stability-control warning light
How it works
The active air dam actuator moves the vehicle’s air dam to manage airflow as the vehicle operates. The control module monitors the actuator control circuit and sets C0603 when its voltage reads higher than expected, which can happen if the wire is contacting battery power or a connection is compromised.
Common causes
Most likely first.
- Wiring shorted to battery
- Connector pins corroded - high contact resistance
- Supply wire pinched against B+ source
Symptoms
- Active air dam warning light may be on
- Active air dam may remain in its current position
How to diagnose it
- Record freeze-frame data and check live data for the active air dam command and circuit status to see when the high reading occurs.
- Inspect the air dam and actuator wiring for chafing, trapped sections, water, or damage that could let a wire touch a B+ source.
- Check the actuator connector for corrosion, loose terminals, pushed-back pins, or damaged seals.
- With the circuit active, gently move the harness while watching scan data to see whether the fault appears or changes.
- Test the control wire for an unintended connection to battery power and check connector contact quality against the manufacturer's procedure.
Common fixes
- Repair a chafed or pinched wire that is contacting battery power.
- Clean or repair corroded, loose, or pushed-back connector terminals.
- Replace damaged connector seals and restore the harness routing.
- Replace the actuator or repair the control module only if circuit tests identify it as faulty.
Can I keep driving?
If the air dam is stuck, ordinary driving may be possible, but avoid assuming the system will adjust airflow as designed. Have the fault checked soon, especially if the dam is loose or could contact the road.
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.