Turbo/Super Charger Underboost
The MAXXFORCE-P0299-11 (MaxxForce) diesel fault code means: Turbo/Super Charger Underboost. This is a serious severity code.
- Keep driving?
- Short distances only
- DIY difficulty
- advanced
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What Are the Symptoms of MAXXFORCE-P0299-11?
- Loss of power, especially under load
- Slow acceleration
- Check Engine light
What Causes MAXXFORCE-P0299-11? (Most Likely First)
- Charge-air leak (cracked charge-air cooler, loose clamp or split hose) High
- Variable-geometry turbo vanes or actuator sticking toward the low-boost position High
- Restricted air intake or exhaust Medium
- Boost pressure sensor reading low Low
Can I Still Drive with MAXXFORCE-P0299-11?
Short distances only. MAXXFORCE-P0299-11 is rated serious severity. Keep trips short and get it diagnosed soon rather than waiting for symptoms to worsen.
Frequently Asked Questions
What does P0299 mean on a MaxxForce?
P0299 means Turbo/Super Charger Underboost. Measured boost pressure stayed below what the engine control module commanded.
Is P0299 a MaxxForce-specific code?
No. P0299 is a generic OBD-II code defined by SAE J2012, so it means the same thing on any vehicle that sets it. The exact conditions Navistar uses to set it on its diesels are in Navistar service information.
Mechanics Guide Step-by-step diagnosis
How Do You Diagnose MAXXFORCE-P0299-11?
Compare commanded and actual boost on a scan tool under load.
Pressure-test the charge-air system for leaks.
Command the turbo actuator through its range and check that it moves freely.
Sources 1
This page is built from documented references. Verify against your own service info before repair work.
- California Code of Regulations, Title 13 section 1971.1 (Heavy-Duty OBD)malfunction criteria, section (e)
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