Turbo Underboost
The MAXXFORCE-P0299-11 (MaxxForce) diesel fault code means: Turbo Underboost. This is a serious severity code.
- Keep driving?
- Short distances only
- DIY difficulty
- advanced
- Estimated cost
- $800-$6,000
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What Are the Symptoms of MAXXFORCE-P0299-11?
- Low power
- Derate
- CEL
What Causes MAXXFORCE-P0299-11? (Most Likely First)
- VGT vane actuator failure Very Likely
- Plugged or cracked high-pressure turbo Likely
- Exhaust restriction from plugged DPF Possible
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 is P0299 on a MaxxForce 11 (10.5L)?
P0299 on a MaxxForce 11 (10.5L) (2008-2014) indicates: Turbo Underboost. This is a known fault code on the MaxxForce engine family and typically points to the causes listed above.
Can I drive with P0299 on my MaxxForce?
Only drive short distances to reach a repair facility. Continued operation may cause further damage or progressive derate.
How much does it cost to fix MaxxForce P0299?
Repair cost is typically $800-$6,000 depending on the underlying cause and shop rate. Many MaxxForce faults (especially EGR cooler, head bolt, and VGT repairs) are major expenses that drove fleet owners to repower with Cummins or retire these trucks early.
What actually makes the computer set this boost code?
California's heavy-duty OBD regulation sets the underboost trip point where a decrease from commanded or expected boost would push NMHC, CO or NOx past 2.0 times the applicable standards, or PM past the standard plus 0.02 g/bhp-hr (Title 13 CCR 1971.1, section (e)(4.2.1)). As with EGR, it must also flag the system reaching its control limits without achieving commanded boost — worth knowing before condemning a turbo that is physically moving. This threshold comes from the heavy-duty OBD regulation, which covers 2010 and later heavy-duty engines. If your engine is in a pickup at or under 14,000 lb GVWR it is certified under the separate medium-duty rule instead, so treat this as the design intent rather than your engine's exact limit.
Mechanics Guide Step-by-step diagnosis
How Do You Diagnose MAXXFORCE-P0299-11?
Inspect VGT operation via service tool.
Check high-pressure turbo shaft play.
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)
Which Vehicles Commonly Get MAXXFORCE-P0299-11?
- International ProStar MaxxForce 11
- International TranStar 8600 MaxxForce 11
- International PayStar 5900 MaxxForce 11
- International WorkStar 7600 MaxxForce 11
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