Exhaust Gas Recirculation Flow Insufficient Detected
The MAXXFORCE-P0401-DT (MaxxForce) diesel fault code means: Exhaust Gas Recirculation Flow Insufficient Detected. This is a serious severity code.
- Keep driving?
- Yes, but fix soon
- DIY difficulty
- intermediate
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What Are the Symptoms of MAXXFORCE-P0401-DT?
- Check Engine light
- Possible reduced power or higher exhaust temperatures
What Causes MAXXFORCE-P0401-DT? (Most Likely First)
- EGR valve sticking closed from soot build-up High
- Restricted or plugged EGR cooler High
- EGR flow, position or differential-pressure sensor reading wrong Medium
Can I Still Drive with MAXXFORCE-P0401-DT?
Yes, but fix soon. MAXXFORCE-P0401-DT is rated serious severity. It is not an immediate stop-driving fault, but it will not clear itself — book the repair rather than ignoring it.
Frequently Asked Questions
What does P0401 mean on a MaxxForce?
P0401 means Exhaust Gas Recirculation Flow Insufficient Detected. The control module measured less EGR flow than it commanded.
Is P0401 a MaxxForce-specific code?
No. P0401 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-P0401-DT?
Command the EGR valve on a scan tool and compare commanded and actual position.
Inspect the EGR valve and passages for soot build-up.
Check the EGR cooler for restriction.
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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