Easy one-page printout for the garage or repair shop
This summary uses the existing diagnostic information shown in full below.
This code means that the car's computer found a problem with the part that controls the moving panel under the front of the car. It's like a flap that helps the car move better by changing its shape. The computer thinks the flap is getting too much power.
The C0603 code indicates that the voltage in the circuit controlling the active air dam is higher than expected. This can be due to a short circuit or a malfunctioning component.
The active air dam is a component that adjusts the airflow under the vehicle to improve aerodynamics and fuel efficiency. The control circuit for this component is monitored by the vehicle's computer. A 'high' signal indicates an abnormally high voltage, suggesting a potential short to power or a faulty control module.
• Check Engine Light or Service Vehicle Soon warning light
• Reduced fuel efficiency
• Unusual noises from the front of the vehicle
• Short circuit in the wiring harness
• Faulty active air dam actuator
• Malfunctioning control module
Active Air Dam: A component that adjusts to improve vehicle aerodynamics.
Control Circuit: An electrical circuit that manages the operation of a component.
• Use a scan tool to verify the code.
• Inspect the wiring harness for shorts or damage.
• Test the active air dam actuator for proper operation.
• Repair or replace damaged wiring.
• Replace the active air dam actuator if faulty.
• Replace or reprogram the control module if necessary.
• OBD-II scan tool
• Multimeter
• Basic hand tools
$150 - $500
Moderate
• Chevrolet Silverado
• GMC Sierra
• Cadillac Escalade
• Regularly inspect and maintain vehicle wiring.
• Ensure active air dam is free of debris and damage.
• Follow manufacturer service schedules.
Control Circuit Issue
• Avoid driving at high speeds until the issue is resolved.
• Consult a professional mechanic for accurate diagnosis.
Check with the vehicle manufacturer for warranty coverage on emissions-related components.
This code has been associated with vehicles using active aerodynamic components to improve fuel efficiency.
Moderate – While the vehicle may still be drivable, it is advisable to address the issue to prevent further damage and maintain fuel efficiency.
Ignoring this code may lead to increased emissions, which could affect compliance with environmental regulations.
• Vehicle running at operating temperature
• Active air dam engaged
The active air dam is located at the front lower section of the vehicle, typically under the front bumper.
Q: Can I drive with the C0603 code?
A: While the vehicle may still be drivable, it is recommended to address the issue to prevent reduced fuel efficiency and potential damage.
Q: What happens if I ignore the C0603 code?
A: Ignoring the code can lead to reduced fuel efficiency and possible damage to the active air dam system.
Pro · Four-system diagnostics
A handheld scanner aimed at engine, transmission, ABS, and airbag diagnostic work.
Chassis and ABS faults usually need a scanner that can read brake-system data directly.
View on Amazon
Universal · Torque wrench
Useful when reassembly torque matters for wheel, suspension, and under-hood fasteners.
Useful when wheel, hub, or suspension hardware needs correct reassembly torque.
View on Amazon
Universal · Drive-on ramps
Helpful for safer access underneath the vehicle during exhaust, EVAP, and underbody inspection work.
Helpful for safer access during underbody inspection work.
View on AmazonThese are optional diagnostic tools, not guaranteed fixes. As an Amazon Associate I earn from qualifying purchases.