AutoCodes – GMC – C0299 2015 GMC Sierra

C0299 2015 GMC Sierra Code - Brake Booster Large Vacuum Leak Detected

Quick Answer

The brake booster vacuum sensor measures the vacuum in the brake booster assembly. Common causes include Vacuum leak at the brake booster, Faulty Brake Booster Vacuum Sensor, Brake Booster Vacuum Sensor harness is open or shorted. 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: C0299 2015 GMC Sierra indicates Brake Booster Large Vacuum Leak Detected.
Common causes: Common causes include Vacuum leak at the brake booster, Faulty Brake Booster Vacuum Sensor, Brake Booster Vacuum Sensor harness is open or shorted.
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 402

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 05, 2023

Description
Possible Causes
How To Fix
Cost to Diagnose
FAQs
Comments
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Code C0299 2015 GMC Sierra Description

The brake booster vacuum sensor measures the vacuum in the brake booster assembly. The Electronic Brake Control Module (EBCM) supplies a 5 V reference and a low reference circuit to the brake booster vacuum sensor. The vacuum sensor supplies a voltage signal in relation to the pressure in the brake booster to the Electronic Brake Control Module. The Diagnostic Trouble Code (DTC) will be set when the Electronic Brake Control Module detected a too-low vacuum in the brake booster assembly.

OBDII Code C0299 2015 GMC Sierra - Brake Booster Large Vacuum Leak Detected - AutoCodes.com — C0299 2015 GMC Sierra Code - Brake Booster Large Vacuum Leak Detected

What does this mean?

What are the Possible Causes of the DTC C0299 2015 GMC Sierra?

Vacuum leak at the brake booster
Faulty Brake Booster Vacuum Sensor
Brake Booster Vacuum Sensor harness is open or shorted
Brake Booster Vacuum Sensor circuit poor electrical connection
Faulty Electronic Brake Control Module (EBCM)

How to Fix the DTC C0299 2015 GMC Sierra?

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 C0299 2015 GMC Sierra 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.

Need more information about the C0299 2015 GMC Sierra code?

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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 C0299 2015 GMC Sierra Code

What does the OBDII code C0299 mean on a 2015 GMC Sierra?

C0299 indicates that the vehicle has detected a large vacuum leak in the brake booster system, which is critical for proper braking assist.

What are the common symptoms of the C0299 code on a 2015 GMC Sierra?

Symptoms include a hard brake pedal, reduced braking performance, hissing noises near the brake pedal, and possible illumination of the ABS or brake warning light.

What causes the C0299 code on a 2015 GMC Sierra?

The most common causes are a damaged brake booster, a leaking vacuum hose, a faulty check valve, or insufficient engine vacuum due to engine issues.

Can I drive my 2015 GMC Sierra with the C0299 code?

It is not recommended to drive with this code active, as the braking system may not function correctly, increasing the risk of an accident.

How do I diagnose the C0299 code on my GMC Sierra?

Inspect the brake booster, vacuum hoses, and check valve for damage or leaks. Use a vacuum gauge to test for proper vacuum levels and verify the brake booster is functioning correctly.

What repairs can fix the C0299 code on a 2015 GMC Sierra?

Repairs may include replacing a damaged brake booster, repairing or replacing leaking vacuum hoses, replacing a faulty check valve, or addressing any engine vacuum issues.

How much does it cost to fix the C0299 code on a 2015 GMC Sierra?

Repair costs can range from $150 to $800, depending on whether the issue is a simple vacuum hose replacement or a complete brake booster replacement.

What tools are needed to troubleshoot the C0299 code?

Tools may include a vacuum gauge, a scan tool to clear codes, and basic hand tools for inspecting and replacing components.

Can poor engine performance trigger the C0299 code?

Yes, if the engine is not producing adequate vacuum (due to issues like a vacuum leak or low compression), it can cause the C0299 code to appear.

Will resetting the code fix the C0299 issue on my GMC Sierra?

No, resetting the code will only clear the warning temporarily. The underlying issue must be diagnosed and repaired to prevent the code from returning.