AutoCodes – Buick – C0166 Buick

C0166 Buick Code - TCS Priming Line Valve Circuit Malfunction

Quick Answer

The Master Cylinder Isolation Valve, or TCS Prime Valve Solenoid circuits are supplied with battery power when the ignition is in the RUN position. Common causes include Faulty TCS Prime Valve Solenoid, TCS Prime Valve Solenoid harness is open or shorted, TCS Prime Valve Solenoid 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: C0166 Buick indicates TCS Priming Line Valve Circuit Malfunction.
Common causes: Common causes include Faulty TCS Prime Valve Solenoid, TCS Prime Valve Solenoid harness is open or shorted, TCS Prime Valve Solenoid 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 1,200

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 May 08, 2020

Description
Possible Causes
How To Fix
Cost to Diagnose
FAQs
Comments
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Code C0166 Buick Description

The Master Cylinder Isolation Valve, or TCS Prime Valve Solenoid circuits are supplied with battery power when the ignition is in the RUN position. The Electronic Brake Control Module (EBCM) controls the valve functions by grounding the circuit when necessary.

OBDII Code C0166 Buick - TCS Priming Line Valve Circuit Malfunction - AutoCodes.com — C0166 Buick Code - TCS Priming Line Valve Circuit Malfunction

What does this mean?

What are the Possible Causes of the DTC C0166 Buick?

Faulty TCS Prime Valve Solenoid
TCS Prime Valve Solenoid harness is open or shorted
TCS Prime Valve Solenoid circuit poor electrical connection

How to Fix the DTC C0166 Buick?

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 C0166 Buick 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 C0166 Buick Code

1. What does the OBDII code C0166 mean on a Buick?

C0166 indicates a malfunction in the TCS (Traction Control System) priming line valve circuit, which may affect the vehicle's traction control and stability systems.

2. What are the common symptoms of code C0166 in a Buick?

Common symptoms include the ABS or traction control light illuminating, reduced traction control functionality, and possibly erratic braking behavior.

3. What causes the C0166 code to appear?

The code can be triggered by a faulty TCS priming line valve, wiring issues like damaged or corroded connectors, or problems with the ABS module.

4. Can I still drive my Buick with the C0166 code?

While the vehicle may still be drivable, traction control and ABS functionality could be compromised, making it unsafe to drive in slippery or emergency situations.

5. How do I diagnose the C0166 code in my Buick?

Diagnose the issue by checking the wiring and connectors for the TCS priming line valve circuit, scanning for additional codes, and testing the functionality of the TCS valve with a multimeter or scan tool.

6. What repairs are typically needed to fix code C0166?

Repairs may include replacing the faulty TCS priming line valve, repairing or replacing damaged wiring or connectors, or reprogramming or replacing the ABS control module.

7. How much does it cost to fix code C0166 on a Buick?

Repair costs can vary but generally range from $150 to $600, depending on the extent of the wiring or component damage and labor rates.

8. Can a failing ABS module cause the C0166 code?

Yes, a failing ABS module can cause the code if it is not properly communicating with the TCS priming line valve circuit.

9. Will clearing the C0166 code fix the issue permanently?

No, clearing the code without addressing the root cause will only temporarily erase it, and the issue will likely return.

10. Can a low brake fluid level trigger the C0166 code?

While low brake fluid is not a direct cause, it may contribute to other issues in the braking system that could indirectly affect the TCS and ABS systems.