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Code C0604

Symptoms

• Reduced fuel efficiency

• Check engine light on

• Unusual noises from the front of the vehicle

Common Causes

• Faulty active air dam actuator

• Wiring issues in the control circuit

• Faulty control module

Glossary

Active Air Dam: A component that adjusts to improve aerodynamics.

Actuator: A device that moves or controls a mechanism or system.

Related Codes

• C0605

• C0606

Laymans terms

This code means there's a problem with the part of the car that helps control air flow to make the car more efficient. It's like a flap that opens and closes, and right now it's not working right.

Explanation

The C0604 code is triggered when the vehicle's computer detects a problem with the active air dam control circuit, which is responsible for adjusting the position of the air dam to optimize aerodynamics.

Technical description

The active air dam is a component that adjusts its position based on vehicle speed and other parameters to improve aerodynamic efficiency. The control circuit for this system monitors and adjusts the air dam's position. A performance issue in this circuit indicates that the system is not operating as expected, which could be due to electrical or mechanical faults.

Diagnosis steps

• Inspect the active air dam for physical damage.

• Check the wiring and connectors for signs of damage or corrosion.

• Test the actuator and control module for proper operation.

Repair procedures

• Replace the faulty air dam actuator.

• Repair or replace damaged wiring or connectors.

• Replace the control module if necessary.

Tools required

• OBD-II scanner

• Multimeter

• Basic hand tools

Estimated repair cost

$200 - $600

Difficulty level

Moderate

Commonly affected vehicles

• Chevrolet Silverado

• GMC Sierra

• Cadillac Escalade

Preventive measures

• Regularly inspect the air dam for damage.

• Keep the vehicle's electrical system in good condition.

• Avoid driving over debris that could damage the air dam.

Error code type

Control System Issue

User experience recommendations

• Have the vehicle inspected by a professional if you notice decreased fuel efficiency.

• Do not ignore the check engine light.

Warranty information

Check with the vehicle manufacturer for warranty coverage on emissions-related components.

Historical data

This code has become more common with the introduction of active aerodynamic components in modern vehicles.

Urgency level

Moderate – While not immediately dangerous, it can affect fuel efficiency and should be addressed soon.

Legal and safety notice

Driving with a malfunctioning air dam may not be illegal, but it can reduce vehicle efficiency and increase emissions.

Testing conditions

• Vehicle at operating temperature

• Vehicle speed above 30 mph

Component location

The active air dam is located at the front lower section of the vehicle, typically under the bumper.

FAQs

Q: Can I drive with a C0604 code?
A: Yes, but it's best to get it fixed soon to avoid reduced fuel efficiency.

Q: How does an active air dam improve efficiency?
A: It reduces aerodynamic drag by adjusting its position based on speed, improving fuel economy.

Last updated: Jun 8, 2026 • Source: internal database
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