P0299 Code: Causes and Fixes

By Carista Team

P0299 Code: Causes and Fixes

Key Takeaways

  • P0299 is an OBD2 diagnostic error code (DTC) for “Turbocharger/Supercharger Underboost Condition.”
  • It signals the engine is not generating enough intake pressure or boost pressure.
  • Symptoms include loss of power, check engine light, and limp mode.
  • Causes range from leaks and faulty pressure sensors to failing turbo components.
  • A reliable OBD2 scanner like Carista helps diagnose P0299 with live boost pressure data, freeze frame information, and detailed fault codes.

What Is the P0299 Code?

The P0299 OBD2 error code is defined as “Turbocharger/Supercharger Underboost Condition.”

From a technical perspective, the engine control module (ECM) or powertrain control module (PCM) has detected an issue. The actual intake pressure is lower than the boost pressure that was set. This is measured by the manifold absolute pressure (MAP) sensor or boost pressure sensor for a specific operating condition.

 

P0299 Code Meaning: Symbol-by-Symbol Breakdown

  • P → Powertrain

    1. This means the fault relates to the engine or transmission system.

  • 0 → Generic Code

    1. A “0” in the second position means it’s a SAE-standard (generic) code used across all makes and models.

    2. If it were a “1,” it would mean a manufacturer-specific code.

  • 2 → Fuel & Air Metering (Injector Circuit)

    1. The “2” identifies the subsystem. Here, it points to fuel and air metering, including injectors, turbo, or supercharger systems.

  • 99 → Specific Fault Identifier

    1. “99” is the specific fault within that subsystem.

    2. In this case, it identifies “Turbocharger/Supercharger Underboost Condition.”

Symptoms of P0299

Drivers may notice one or more of the following:

  • Reduced power: The car feels sluggish, especially during acceleration.
  • Check engine light: The warning light activates on the dashboard.
  • Poor fuel economy: The engine burns more fuel to compensate for low air intake.
  • Whistling or hissing noise: A boost leak may create unusual sounds.
  • Limp mode: In some cars, the ECM restricts power to protect the engine.

Check engine light on a car dashboard

Causes of P0299

Several issues can trigger the P0299 error code:

  1. Boost leaks: Cracked hoses, loose clamps, or intercooler leaks.
  2. Faulty turbocharger/supercharger: Worn bearings, damaged impeller, or wastegate failure.
  3. Defective sensors: Malfunctioning boost pressure sensor or mass airflow (MAF) sensor.
  4. Vacuum system issues: Faulty vacuum lines or solenoids controlling the wastegate.
  5. Exhaust restrictions: Clogged catalytic converter or exhaust leaks before the turbo.
  6. ECM software or calibration issues.

Causes of P0299 by Vehicle Make

Ford (EcoBoost Engines)

  • Common issue: Wastegate actuator failure on EcoBoost turbos.
  • Boost control solenoid problems.
  • Intercooler condensation build-up reducing airflow.
  • Leaks in plastic charge pipes.

Chevrolet / GMC (Duramax & Turbo Gas Engines)

  • Variable geometry turbo (VGT) vanes are sticking because of soot buildup.
  • Faulty MAP (manifold absolute pressure) sensor.
  • Exhaust backpressure sensor problems.
  • Cracked intercooler piping.

Volkswagen / Audi (TSI and TDI Engines)

  • Diverter valve failure causing boost leaks.
  • Wastegate rattle or sticking on smaller turbos (1.8T, 2.0T).
  • EGR or intake manifold issues in TDI diesels.
  • Boost pressure sensor misreadings.

 

How to Fix P0299

Step 1: Scan for Codes

Use a Carista OBD2 scanner to read the error code. Carista provides:

  • Diagnostics to identify the P0299 code and related codes.
  • Freeze frame data to capture the exact conditions when the fault occurred.
  • Live data monitoring to check boost pressure and intake pressure in real time.

Step 2: Inspect for Boost Leaks

Check hoses, clamps, and the intercooler for cracks or looseness. Replace or tighten parts as needed.

Step 3: Test the Turbocharger

Examine the wastegate, turbine blades, and shaft movement. Replace damaged components.

Step 4: Check Sensors and Electronics

Verify that the pressure sensor and MAF sensor are clean and functional.

Step 5: Repair or Replace Components

Replace faulty parts such as vacuum lines, sensors, or the turbocharger itself. Clear the error code with Carista after repairs, then retest under load to confirm boost pressure and intake pressure are within spec.

 

Why Use Carista for Diagnosing P0299?

  • Accurate diagnostics: Read the P0299 error code and related manufacturer-specific codes.
  • Freeze frame data: Understand what was happening when the fault was logged.
  • Live boost and intake pressure data: Monitor turbo performance in real time, making diagnosis faster and more precise.

Carista gives everyday drivers the tools usually reserved for professional mechanics.

 

FAQs About P0299

Is P0299 serious?

Yes. While you may still drive, ignoring P0299 can cause long-term damage to the turbocharger or engine.

Can I drive with a P0299 code?

Short-term driving is possible, but it is not recommended. Reduced intake pressure and low boost pressure mean higher stress on other engine parts.

Does P0299 always mean a bad turbocharger?

No. Many times, the cause is a simple boost leak, faulty pressure sensor, or vacuum problem.

How do I clear a P0299 error code?

After fixing the root cause, use an OBD2 scanner like Carista to clear the code.

Can bad fuel cause P0299?

Not directly. However, poor fuel quality may lead to misfires or knock, which can contribute to underboost conditions indirectly.

 

Disclaimer: This article is for informational purposes only and is not a substitute for professional mechanical advice. Always consult a qualified mechanic for serious automotive issues.