AutoCodes – GMC – P0299 2018 GMC Sierra

P0299 2018 GMC Sierra Code - Engine Underboost

Quick Answer

The Engine Control Module (ECM) uses the Manifold Absolute Pressure (MAP) sensor input and turbocharger actuator output to control the amount of engine induction system boost pressure. Common causes include Faulty Turbocharger Vane Position Actuator, Air leaks between the turbocharger and the intake air flow valve, Airflow restrictions in air ducts or air filter. 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: P0299 2018 GMC Sierra indicates Engine Underboost.
Common causes: Common causes include Faulty Turbocharger Vane Position Actuator, Air leaks between the turbocharger and the intake air flow valve, Airflow restrictions in air ducts or air filter.
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.

Save to My Repairs Step-by-Step Diagnostic Guide My Repairs

AI answers can be wrong. Verify repairs with testing. Open full chat

Code Popularity 332

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 Jun 09, 2022

Description
Step-by-Step Diagnostic Guide
Possible Causes
How To Fix
Cost to Diagnose
FAQs
Comments
Add Comment

💬 Need more help? Ask Coddy for instant answers — it's free!

Code P0299 2018 GMC Sierra Description

The Engine Control Module (ECM) uses the Manifold Absolute Pressure (MAP) sensor input and turbocharger actuator output to control the amount of engine induction system boost pressure. The ECM calculates a desired boost pressure value and monitors the actual boost pressure. If the difference between the actual boost pressure and the desired boost pressure is less than or greater than a calibrated threshold level, the ECM detects that the amount of detected boost pressure is out of range. The Diagnostic Trouble Code (DTC) will be set when the ECM detects the difference between the actual boost pressure and the desired boost pressure in the intake manifold is less than the expected range for 12.5 s. The 12.5 s time is not continuous but cumulative. The timer may sum up a heavy load condition obtained during different maneuvers.

OBDII Code P0299 2018 GMC Sierra - Engine Underboost - AutoCodes.com — P0299 2018 GMC Sierra Code - Engine Underboost

What does this mean?

What are the Possible Causes of the DTC P0299 2018 GMC Sierra?

Faulty Turbocharger Vane Position Actuator
Air leaks between the turbocharger and the intake air flow valve
Airflow restrictions in air ducts or air filter
Ice or debris in the induction system
Leaks at the Positive Crankcase Ventilation (PCV) system
Faulty Turbocharger

How to Fix the DTC P0299 2018 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 P0299 2018 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 P0299 2018 GMC Sierra code?

Need more information on how to fix the P0299 2018 GMC Sierra code? Get Access to Factory Service Manuals

Need Help with the Code?

Get the P0299 2018 GMC Sierra code diagnosed by a professional: Find a repair shop in your area

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 P0299 2018 GMC Sierra Code

1. What does the OBDII code P0299 mean for a 2018 GMC Sierra?

P0299 indicates "Turbocharger/Supercharger Underboost," meaning the engine's turbocharger or supercharger is not generating the expected amount of boost pressure.

2. What are the symptoms of a P0299 code on a 2018 GMC Sierra?

Common symptoms include reduced engine power, poor acceleration, black smoke from the exhaust, and the Check Engine Light turning on.

3. What causes the P0299 code on a 2018 GMC Sierra?

Potential causes include a faulty turbocharger or supercharger, boost leaks, a malfunctioning wastegate, clogged or damaged intercooler, or issues with the boost pressure sensor.

4. Can a dirty air filter cause a P0299 code on a 2018 GMC Sierra?

Yes, a clogged air filter can restrict airflow to the turbocharger, potentially causing an underboost condition.

5. How do you diagnose a P0299 code on a GMC Sierra?

Diagnosis involves inspecting for boost leaks, checking the turbocharger for damage, testing the wastegate and boost pressure sensor, and examining the intercooler and related hoses.

6. Is it safe to drive a 2018 GMC Sierra with a P0299 code?

Driving with a P0299 code is not recommended, as it can lead to reduced performance and potential damage to the engine or turbocharger system.

7. Can a faulty wastegate cause a P0299 code?

Yes, a wastegate stuck open or not functioning properly can prevent the turbocharger from building sufficient boost pressure.

8. How much does it cost to fix a P0299 code on a 2018 GMC Sierra?

Repair costs vary depending on the issue. Fixing a boost leak may cost under $200, while replacing a turbocharger can cost $1,000â€“$2,500 or more.

9. Can a P0299 code be caused by a bad boost pressure sensor?

Yes, a malfunctioning boost pressure sensor can send incorrect readings to the ECU, triggering a P0299 code.

10. How can I prevent a P0299 code on my 2018 GMC Sierra?

Regularly inspect and maintain the turbocharger, intercooler, hoses, and air filter. Address any performance issues promptly to prevent underboost conditions.