P0299 Code – Turbo Underboost (Meaning, Causes, Symptoms & How to Fix)

The P0299 trouble code indicates that your vehicle’s engine control module (ECM) has detected that the turbocharger is producing less boost pressure than expected.

What Does P0299 Mean?

Modern turbocharged engines constantly monitor boost pressure using a MAP sensor.
When the actual boost pressure is significantly lower than the requested value, the ECM triggers:

P0299 – Turbocharger/Supercharger Underboost Condition

In simple terms:
Your turbo is not producing enough pressure.

Common Symptoms of P0299

If your car has a P0299 code, you may notice:

• Loss of engine power

• Slow acceleration

• Limp mode activation

• Check Engine Light ON

• Whistling turbo noise

• Excessive black smoke (diesel engines)

Main Causes of P0299 Code

1. Boost Leak (Most Common)

Cracked hoses, loose clamps, or intercooler leaks allow boost pressure to escape.

2. Faulty Turbocharger

Internal wear, damaged blades, or excessive shaft play reduce boost efficiency.

3. Wastegate Malfunction

If the wastegate is stuck open, the turbo cannot build pressure.

How to Diagnose P0299

Step 1: Scan for Additional Codes

Step 2: Inspect Boost Hoses

Step 3: Check Wastegate Operation

Step 4: Compare Actual vs Requested Boost

Step 5: Inspect Turbocharger Shaft Play

Can You Drive With a P0299 Code?

Driving short distances is possible, but not recommended.
Ignoring the issue can lead to full turbo failure.

Final Thoughts

The P0299 Turbo Underboost code is one of the most common turbo-related issues in modern vehicles.
In many cases, the problem is a simple boost leak rather than a failed turbo.

Early diagnosis saves money.