AutoCodes – GMC – C0660 GMC

C0660 GMC Code - Level Control Exhaust Valve Circuit Malfunction

Quick Answer

The automatic level control adjusts the vehicle suspension ride height. Common causes include Faulty Level Control Exhaust Valve, Level Control Exhaust Valve harness is open or shorted, Level Control Exhaust Valve circuit poor electrical connection. Severity is High - diagnose this code as soon as possible. Driving is not recommended if the warning light is flashing, the engine runs poorly, or safety-related symptoms are present.

What it means: C0660 GMC indicates Level Control Exhaust Valve Circuit Malfunction.
Common causes: Common causes include Faulty Level Control Exhaust Valve, Level Control Exhaust Valve harness is open or shorted, Level Control Exhaust Valve circuit poor electrical connection.
Severity: High - diagnose this code as soon as possible.
Can I drive?: Driving is not recommended if the warning light is flashing, the engine runs poorly, or safety-related symptoms are present.

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Code Popularity 28,784

How popular is this code, among other codes? Low

Repair Importance Level

Urgent (Diagnose now) (3 / 3)

Repair Difficulty Level

Advanced (Pro) (3 / 3)

What is this?

Table of contents Created and updated by William Orellana on Jul 31, 2020

Description
Possible Causes
How To Fix
Tech Notes ▶
Cost to Diagnose
FAQs
Comments
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Code C0660 GMC Description

The automatic level control adjusts the vehicle suspension ride height. The Rear Integration Module (RIM) determines the height of the vehicle based on the voltage from the automatic level control sensor. The RIM raises and lowers the rear of the vehicle in order to keep the vehicle level.

OBDII Code C0660 GMC - Level Control Exhaust Valve Circuit Malfunction - AutoCodes.com — C0660 GMC Code - Level Control Exhaust Valve Circuit Malfunction

What does this mean?

What are the Possible Causes of the DTC C0660 GMC?

Faulty Level Control Exhaust Valve
Level Control Exhaust Valve harness is open or shorted
Level Control Exhaust Valve circuit poor electrical connection

How to Fix the DTC C0660 GMC?

Review the 'Possible Causes' above and visually examine the corresponding wiring harness and connectors. Check for damaged components and inspect connector pins for signs of being broken, bent, pushed out, or corroded.

What does this mean?

Code Tech Notes

User Submitted Video

What is the Cost to Diagnose the Code?

Labor: 1.0

To diagnose the C0660 GMC code, it typically requires 1.0 hour of labor. Rates vary by location, vehicle, and shop. Many shops charge between $80–$150 per hour; dealerships and metro areas may be higher, independents may be lower.

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About the author: William Orellana is a Master Mechanic and Mechanical Engineer with over 30 years of experience diagnosing and repairing vehicles. Learn more about his background.

Frequently Asked Questions about C0660 GMC Code

What does the OBDII code C0660 mean for GMC vehicles?

C0660 refers to a malfunction in the Level Control Exhaust Valve Circuit, which is part of the air suspension system that controls the vehicle's ride height.

What symptoms might indicate a C0660 code?

Common symptoms include a warning light on the dashboard, a rough or uneven ride, the vehicle sitting lower than normal, or an inoperative air suspension system.

What are some common causes of the C0660 code?

Causes may include a faulty level control exhaust valve, damaged wiring or connectors in the circuit, a blown fuse, or issues with the air suspension control module.

How can I diagnose the C0660 code accurately?

Use an OBDII scanner to confirm the code, then visually inspect the wiring and connectors for damage. Perform tests on the level control exhaust valve to check for proper operation.

What repairs might be needed to fix a C0660 code?

Repairs may involve replacing the level control exhaust valve, repairing or replacing damaged wiring or connectors, or replacing the air suspension control module if it is faulty.

Can I clear the C0660 code without fixing the problem?

Yes, you can clear the code with an OBDII scanner, but if the underlying issue is not resolved, the code will likely return.

Is it safe to drive a vehicle with a C0660 code?

While it may still be driveable, the vehicle may have an impaired suspension system, which can affect handling and safety, so it's best to address the issue promptly.

Will a C0660 code affect my vehicle's performance?

Yes, it can lead to an uneven ride height and may cause handling problems, reducing overall vehicle performance and comfort.

What is the average cost to repair a C0660 code?

Repair costs can vary widely depending on the cause but may range from $100 for simple wiring repairs to over $500 for replacing the level control valve or module.