The C0658 diagnostic trouble code (DTC) indicates a problem within the level control (usually air suspension) system, specifically that the voltage in the compressor circuit is higher than expected. This can lead to a malfunctioning or inoperative air suspension system, affecting ride quality, handling, and overall vehicle safety. Addressing this issue promptly is crucial to avoid further damage and ensure optimal vehicle performance.
| Component/Symptom | Description | Possible Cause(s) |
|---|---|---|
| Definition | Level Control Compressor Circuit High Voltage. Indicates the control module has detected voltage exceeding the specified range in the compressor control circuit. | Faulty compressor relay, Wiring harness issues (shorts to voltage, open circuits), Faulty compressor, Faulty control module (e.g., EHCU, Air Suspension Control Module), Corroded connectors. |
| Symptoms | Air suspension not functioning correctly, Vehicle sitting unevenly, "Service Air Suspension" warning light illuminated, Compressor running constantly or not at all, No change in vehicle height when attempting to adjust suspension, Increased ride harshness, Possible compressor overheating, Battery drain. | Relay stuck in the "on" position, Short circuit in the wiring harness supplying voltage to the compressor, Compressor motor failure, Internal control module failure, Air leak in the suspension system (causing prolonged compressor operation). |
| Diagnostic Steps | Visual inspection of wiring and connectors, Check compressor relay function, Measure voltage at the compressor connector, Scan for related DTCs, Test compressor operation with a scan tool, Check for air leaks in the system, Inspect the control module for damage, Perform a resistance test on the compressor motor, Check vehicle battery voltage and charging system. | Damaged wiring harness, Corroded connectors, Defective relay, Faulty compressor, Failed control module, Air leaks in air lines or air struts/springs, Low system pressure due to leak or compressor failure. |
Detailed Explanations
Definition:
The C0658 code signifies that the vehicle's electronic control unit (ECU), specifically the module responsible for managing the air suspension system (often called the EHCU - Electronic Height Control Unit or Air Suspension Control Module), has detected an abnormally high voltage reading in the circuit controlling the air suspension compressor. This circuit is responsible for providing power to the compressor, enabling it to inflate the air springs and maintain the correct vehicle ride height. The "high voltage" condition means the voltage exceeds the pre-programmed acceptable range within the ECU's parameters.
Symptoms:
The symptoms associated with a C0658 code can be quite varied, depending on the severity of the underlying problem. The most common symptom is a malfunction of the air suspension system. This can manifest as the vehicle sitting unevenly (one side lower than the other), or the vehicle failing to maintain the correct ride height. A "Service Air Suspension" warning light on the dashboard is a very common indicator. The compressor might run constantly in an attempt to compensate for a leak or a faulty height sensor, or it might not run at all due to the high voltage condition. Because the air suspension system is not functioning as intended, the ride quality can become harsh and uncomfortable. In extreme cases, a constantly running compressor can overheat and potentially cause a fire hazard, and a short circuit can lead to a battery drain.
Diagnostic Steps:
Diagnosing a C0658 code requires a systematic approach. Begin with a thorough visual inspection of the wiring and connectors associated with the air suspension compressor and its control circuit. Look for any signs of damage, corrosion, or loose connections. Next, check the compressor relay to ensure it is functioning correctly. A faulty relay can cause the compressor to run continuously or not at all. Use a multimeter to measure the voltage at the compressor connector to verify the ECU's reported high voltage. Scan the vehicle's computer for any other related DTCs, as these can provide clues about the root cause of the problem. Use a scan tool that can communicate with the air suspension control module to test the compressor's operation. This allows you to command the compressor on and off and monitor its performance. Check for air leaks in the suspension system, as a leak can cause the compressor to run excessively, potentially leading to a high voltage condition. Inspect the control module for any signs of physical damage or corrosion. Perform a resistance test on the compressor motor to check for internal shorts or open circuits. Finally, check the vehicle's battery voltage and charging system to rule out any issues with the electrical system that could be contributing to the problem.
Possible Causes:
Several factors can contribute to a C0658 code. A faulty compressor relay that is stuck in the "on" position can cause the compressor to run continuously, leading to overheating and a high voltage condition. A short circuit in the wiring harness supplying voltage to the compressor can directly cause the voltage to exceed the specified range. Failure of the compressor motor itself can also trigger the code. In some cases, the internal control module may be faulty, misinterpreting voltage readings or sending incorrect signals to the compressor. An air leak in the suspension system can cause the compressor to run excessively to compensate, potentially leading to a high voltage condition. Corroded connectors can cause resistance and voltage fluctuations.
Frequently Asked Questions
What does the C0658 code mean?
It signifies that the air suspension control module has detected excessively high voltage in the compressor control circuit.
Can I still drive my car with this code?
It's not recommended, as the air suspension may not function correctly, affecting handling and safety. It can also cause further damage.
Is the C0658 code a serious problem?
Yes, it indicates a potentially serious issue with the air suspension system that needs prompt attention.
How do I fix a C0658 code?
Diagnosis is key; follow the diagnostic steps outlined above to identify and repair the underlying cause, which could range from a faulty relay to a damaged compressor.
Can a bad air suspension compressor cause this code?
Yes, a failing compressor can draw excessive current, leading to a high voltage condition.
Could a bad battery cause a C0658 code?
While less common, a significantly low or unstable battery voltage can sometimes trigger unusual error codes in various vehicle systems.
Conclusion
The C0658 code highlights a potentially significant problem within the air suspension system. Prompt and accurate diagnosis is crucial to identify the root cause, ranging from simple wiring issues to more complex component failures. Addressing this code promptly will help restore proper air suspension functionality, ensuring a comfortable ride and maintaining vehicle safety.