What is an OBD2 code?

An OBD2 (On-Board Diagnostics) code is a diagnostic trouble code (DTC) generated by your vehicle's computer system when it detects a problem. These codes help identify specific issues with your vehicle's engine, transmission, emissions, or other systems.

How do I read OBD2 codes?

To read OBD2 codes, you'll need an OBD2 scanner. Plug it into your vehicle's OBD2 port (usually located under the dashboard), turn your key to the 'ON' position, and follow your scanner's instructions to retrieve the codes. Each code starts with a letter (P, B, C, or U) followed by four numbers.

What do the different types of OBD2 codes mean?

OBD2 codes are categorized by their first letter: P (Powertrain) for engine and transmission issues, B (Body) for interior systems like airbags, C (Chassis) for mechanical systems like brakes, and U (Network) for computer and module communication problems.

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Home » OBD2 Codes » C0666

Code C0666

Symptoms

• Bumpy or uncomfortable ride

• Warning light on the dashboard

• Unusual noises from the suspension

Common Causes

• Faulty suspension control module

• Damaged wiring or connectors

• Faulty suspension position sensor

Glossary

ECU: Electronic Control Unit

OBD-II: On-Board Diagnostics II

Related Codes

• C0665

• C0667

Laymans terms

This code means there's a problem with the car's suspension system, which helps make rides smooth and comfortable.

Explanation

The C0666 code indicates an issue with the vehicle's suspension control system.

Technical description

The C0666 code is related to the suspension control system, which may involve the electronic control unit (ECU) failing to communicate properly with the suspension components, leading to impaired suspension performance.

Diagnosis steps

• Check for any visible damage to suspension components.

• Use a diagnostic scanner to read and clear codes.

• Inspect wiring and connectors for damage or corrosion.

Repair procedures

• Replace faulty suspension control module.

• Repair or replace damaged wiring or connectors.

• Replace faulty suspension position sensor.

Tools required

• OBD-II scanner

• Multimeter

• Basic hand tools

Estimated repair cost

$200 - $800

Difficulty level

Moderate

Commonly affected vehicles

• Chevrolet Tahoe

• GMC Yukon

• Cadillac Escalade

Preventive measures

• Regularly inspect suspension components.

• Keep electrical connections clean and dry.

• Perform routine maintenance checks.

Error code type

Suspension System Issue

User experience recommendations

• Avoid driving on rough terrain until fixed.

• Consult with a professional mechanic for accurate diagnosis.

Warranty information

Check with your vehicle manufacturer for warranty coverage on suspension components.

Historical data

C0666 has been reported in vehicles with advanced suspension systems, particularly in models with electronic control.

Urgency level

Moderate – The vehicle can be driven, but the ride quality may be affected.

Legal and safety notice

Ensure repairs are conducted by a qualified technician to maintain vehicle safety and compliance.

Testing conditions

• Vehicle must be on a level surface.

• Suspension system should be at normal operating temperature.

Component location

The suspension control module is typically located near the vehicle's chassis or under the hood.

FAQs

Q: Can I drive with a C0666 code?
A: Yes, but the ride may be uncomfortable. It's best to have it checked soon.

Q: What happens if I ignore this code?
A: Ignoring it can lead to further suspension damage and a less comfortable ride.

Last updated: May 17, 2026 • Source: internal database

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