Mercedes P0299 Turbo Underboost – OM270 Engine

System: Engine / Boost System
Component: Turbocharger
Engine: OM270

Fault Codes

• P0299 – Turbocharger 1 boost pressure too low

Typical Symptoms

• Engine warning light illuminated
• Reduced engine power
• Poor acceleration
• Vehicle may enter limp mode

Possible Cause

• Boost leak (hoses / intake pipes)
• Faulty turbocharger
• Wastegate or actuator fault
• Boost pressure sensor issue
• Air intake leak

Diagnostic Insight

This fault indicates that the engine is not achieving the required boost pressure.

Technicians usually check:

• boost pressure readings using live data
• intake and boost pipes for leaks
• turbocharger operation
• actuator or wastegate function

It is important to cross-check all related faults and components before replacing the turbocharger.

In this case, after testing confirmed no leaks or control faults, the turbocharger itself was faulty and required replacement.

Important Note

P0299 is often caused by boost leaks or control issues, not always the turbocharger.

Full system testing should always be carried out before replacing major components.

⚠ Professional Diagnostic Recommended

Turbocharger and boost system faults require specialist diagnostic equipment. The vehicle should be inspected by a Mercedes-Benz dealer or qualified Mercedes specialist.