What Does C0663 Mean?
This code indicates the suspension control module has detected an abnormally high voltage in the level control exhaust valve circuit. The air suspension system uses exhaust valves to release air from the suspension airbags to lower the vehicle or maintain proper ride height. A high circuit voltage typically means the control module is seeing more voltage than expected when commanding the exhaust valve, suggesting a short to power, open circuit, or internal valve failure.
Common Causes
40%
Wiring harness damage causing short to voltage (power) in the exhaust valve circuit, often from chafing against chassis or component mounting
35%
Failed level control exhaust valve solenoid with internal short or open coil windings
15%
Corroded or damaged electrical connector at the exhaust valve causing high resistance or open circuit
10%
Faulty suspension control module with internal driver circuit failure
Diagnostic Steps
1
Step 1: Perform visual inspection of the exhaust valve wiring harness from the suspension control module to the valve, checking for obvious damage, chafing, pinching, or corrosion at all connectors. Pay special attention to areas where harness routes near sharp edges or moving components.
2
Step 2: Disconnect the exhaust valve connector and inspect terminals for corrosion, bent pins, or moisture intrusion. Use a multimeter to measure resistance across the valve solenoid coil (typically 3-8 ohms depending on manufacturer). An infinite reading indicates open circuit, near-zero indicates short.
3
Step 3: With valve disconnected, check voltage at the valve harness connector while commanding the valve active with the scan tool. Reading should show battery voltage when commanded ON and near 0V when commanded OFF. Constant high voltage indicates wiring short to power.
4
Step 4: If wiring and valve test normal, measure the control circuit voltage at the suspension module connector while monitoring commanded state. Compare readings to manufacturer specifications (typically 0-1V OFF, 12-14V ON). Inconsistent readings suggest module driver circuit failure.
5
Step 5: After repairs, clear codes, perform suspension system calibration/relearn procedure if required, cycle the exhaust valve multiple times using scan tool commands, and verify proper voltage levels and no return of the code during a test drive with multiple ride height changes.
Estimated Repair Cost
$150 - $800
Parts + labor, varies by vehicle and location
This code indicates the suspension control module has detected an abnormally high voltage in the level control exhaust valve circuit. The air suspension system uses exhaust valves to release air from the suspension airbags to lower the vehicle or maintain proper ride height. A high circuit voltage t...
The most common cause of C0663 (Level Control Exhaust Valve Circuit High) is: Wiring harness damage causing short to voltage (power) in the exhaust valve circuit, often from chafing against chassis or component mounting
Typical repair costs for C0663 range from $150 to $800, depending on the vehicle, location, and whether you do it yourself or go to a shop.
Vehicle is safe to drive but may experience improper ride height, inability to adjust suspension level, or locked ride height. The vehicle may sit higher or lower than normal and ride quality may be compromised. Repair within a few days to prevent potential damage to suspension components or uneven tire wear.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to C0663 to identify the root cause.
OBDHut Mobile App
Scan codes directly from your car with the OBDHut app.
Coming Soon
Quick Info
Category
Chassis
System
Air Suspension / Ride Height Control System
Difficulty
Type
Generic (SAE)
Recommended Tools
OBD2 Scanner
A quality scan tool helps you read codes, view live data, and clear faults.
