If you get “Exhaust System Warning” along with a check engine light, and had replaced every sensor and even the catalytic converter with multiple dealers, but the warning and check light persist, keep reading.
In this article, I will cover the causes of warning and check light, non-delete tips to help solve the problem, and delete route.
What Causes Exhaust System Warnings on 6.7 Cummins?
Root Cause: Your Emissions System is Complex.
Modern 6.7 Cummins OE emissions system includes DPF (Diesel Particulate Filter), SCR (Selective Catalytic Reduction), DEF (Diesel exhaust fluid), EGR (Exhaust Gas Recirculation), and a lot of sensors (e.g. NOx, temp, pressure, etc.)
These components all rely on each other. When one starts to fail—or even gives slightly incorrect data—your ECU flags it.
Common Failure Components are DEF, DPF, EGR, and Sensors
DEF system: DEF crystallization, clogged injectors, or contaminated fluid can throw the whole system off.
DPF clogging: Short trips and towing without proper regen cycles lead to soot buildup.
EGR soot buildup: Recirculated exhaust increases carbon buildup, affecting airflow and readings.
NOx sensor failure: These sensors fail frequently and are expensive—and replacing them doesn’t always fix the root issue.
Why Do Check Engine Light & Exhaust Warning Show Up Together?
It’s All Connected
When the exhaust system throws a warning, the ECU also logs fault codes—that’s your check engine light. So when you see both at once, it usually means this issue isn’t temporary—it’s something the ECU considers serious.
Why Replacing Parts Didn't Work?
The system is interdependent that sensors might give misleading readings, also, root causes like soot buildup or DEF contamination remain after parts replacement.
For many diesel owners, the question becomes: Do I keep fighting the system… or eliminate the problem?
Non-Delete Route: How to Prevent It in the Future
Regularly Drive on Highways
Short trips kill emissions systems, you need regular highway driving to allow proper regen cycles.
Routine checks on the Emission System
Be proactive on your system, and conduct health checks on it thoroughly on a regular basis. For DEF, use high-quality fluid to avoid contamination, and again, don’t let it sit for too long.
Clean Key Components from time to time
Keep your MAP sensor, EGR system, and intake system clean to reduce false readings and soot buildup.
Delete Route
It is a hard decision to make, but hear those other owners out:
R. S. said, "Delete it you will never have that issue again"
C. C. said, "I deleted mine and forgo the warranty….no issues since"
Ready to say bye to emission headaches? We offer you 3 different delete kit featuring different tuners.
All-in-One Delete Kit for 2019–2021 6.7 Cummins
If you’re considering this route, doing it right matters.
Our all-in-one delete kits for 2019-2021 6.7 Cummins include:
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EZ Lynk AutoAgent + Delete hardware (DPF + EGR delete)
- No ECM swap required. Flash your factory ECM directly through the OBD2 port. Starting at $1,749.99.
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EFI Live + Delete hardware (DPF + EGR delete)
- Vehicle & year specific tuning. Starting at $1,355.00.
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Mini Maxx V2 + Delete hardware (DPF + EGR delete)
- Only supports the original PCM software with part number that starts with a number. Starting at $1,379.00.
Everything is designed to work together—no piecing parts together, no compatibility issues.
Either way, now you know what’s actually going on—and can make the right call for your Ram 👍
