AutoCodes – GMC – C0665 GMC

C0665 GMC Code - Level Control Compressor Relay Malfunction

Quick Answer

The Electronic Suspension Control (ESC) module monitors a lift/dive signal at the Powertrain Control Module (PCM). Common causes include Faulty Level Control Compressor Relay, Level Control Compressor Relay harness is open or shorted, Level Control Compressor Relay 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: C0665 GMC indicates Level Control Compressor Relay Malfunction.
Common causes: Common causes include Faulty Level Control Compressor Relay, Level Control Compressor Relay harness is open or shorted, Level Control Compressor Relay 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 864

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
Cost to Diagnose
FAQs
Comments
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Code C0665 GMC Description

The Electronic Suspension Control (ESC) module monitors a lift/dive signal at the Powertrain Control Module (PCM). Under normal conditions, the ESC module supplies a 5-volt reference voltage to the PCM. The PCM grounds this circuit when the vehicle is accelerating rapidly (LIFT) or braking hard (DIVE). When the lift/dive signal goes low (approximately 0-volts), the ESC module commands all four ESC dampers to a FIRM condition.

OBDII Code C0665 GMC - Level Control Compressor Relay Malfunction - AutoCodes.com — C0665 GMC Code - Level Control Compressor Relay Malfunction

What does this mean?

What are the Possible Causes of the DTC C0665 GMC?

Faulty Level Control Compressor Relay
Level Control Compressor Relay harness is open or shorted
Level Control Compressor Relay circuit poor electrical connection

How to Fix the DTC C0665 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 is the Cost to Diagnose the Code?

Labor: 1.0

To diagnose the C0665 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 C0665 GMC Code

1. What are the common symptoms of OBDII code C0665 GMC (Level Control Compressor Relay Malfunction)?

The common symptoms of this code include issues with the vehicle's air suspension system, such as erratic ride height, a sagging rear end, or difficulty maintaining proper vehicle level.

2. What can cause the OBDII code C0665 GMC to trigger?

This code is typically triggered by a malfunction in the level control compressor relay, which may be due to a faulty relay, wiring issues, or a problem with the compressor itself.

3. How serious is the Level Control Compressor Relay Malfunction indicated by OBDII code C0665 GMC?

While this code does not pose an immediate safety risk, it can affect the overall performance and ride quality of your vehicle, especially if it pertains to the air suspension system.

4. Can I continue driving my vehicle with OBDII code C0665 GMC present?

It is generally not recommended to continue driving with this code active, as it can lead to further damage to the air suspension system and potentially compromise the vehicle's handling and ride comfort.

5. How can I diagnose and repair OBDII code C0665 GMC at home?

Diagnosing this code may involve checking the relay, inspecting the wiring for any damage, and testing the compressor for proper functionality. Repair typically involves replacing the faulty relay or addressing any wiring issues.

6. Is it possible to reset OBDII code C0665 GMC without fixing the underlying issue?

Resetting the code without addressing the root cause, such as a faulty relay or compressor, is not recommended as the issue will likely reoccur, leading to ongoing problems with the air suspension system.

7. Are there any preventive maintenance tips to avoid OBDII code C0665 GMC in the future?

To prevent this code from reoccurring, it is advisable to regularly inspect and maintain the air suspension system components, including the compressor, relay, and associated wiring.

8. Can a DIY enthusiast with basic automotive knowledge fix OBDII code C0665 GMC?

Depending on your skill level and comfort working with automotive electrical systems, you may be able to diagnose and replace the faulty components causing this code. However, professional assistance is recommended if you are unsure.

9. How long does it typically take to repair OBDII code C0665 GMC at a repair shop?

The repair time for this code can vary depending on the exact cause of the issue and the availability of replacement parts. In general, it may take a few hours to a full day for a repair shop to diagnose and fix the problem.

10. Will fixing OBDII code C0665 GMC improve my vehicle's performance and ride quality?

Correcting the Level Control Compressor Relay Malfunction indicated by this code should help restore proper functionality to the air suspension system, leading to improved ride quality and vehicle performance.