⚠️ LEGAL DISCLAIMER: OFF-ROAD USE ONLY
The following content discusses the removal of emissions equipment, which is intended solely for off-road competition use. Modifying emission systems is illegal for street use in the United States and Canada.
Author: Lawrence Z, Diesel Performance Specialist at DPFexhaust
If you own a 2011–2016 Chevy Silverado or GMC Sierra 2500/3500 HD (LML Duramax), you know exactly what the "Square Tumor" is.
Unlike newer trucks where the DEF tank is somewhat tucked away, GM mounted the LML DEF tank low on the passenger side frame rail.
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It’s Ugly: It ruins the clean lines of a lifted or leveled truck.
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It’s a Hazard: For farm and off-road trucks, it kills your ground clearance and is prone to getting smashed by rocks or stumps.
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It’s Unreliable: The heater inside is notorious for failing (Code P20BD).
Many owners search for a "DEF Tank Removal Kit," but often end up with just a generic exhaust pipe. Here is what a Complete removal actually looks like and why you need more than just software.
1. What Defines a "Complete" Removal Kit?
You cannot simply unbolt the tank and drive away. The truck will throw codes and enter limp mode immediately. A truly complete solution involves a three-stage process:
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The Brain (Tuner): You must first flash the ECU (using EFI Live or EZ Lynk) to tell the truck the DEF system no longer exists. Do not unplug anything until this is done.
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The Bypass (Exhaust): You replace the section of the exhaust pipe that houses the DEF injector. Not sure the difference between an aluminized exhaust and a stainless steel exhaust? Check Aluminized vs. Stainless Steel Exhaust.
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The Physical Drop (The Tank Kit): This is the step most people overlook. You physically unbolt the tank straps, lower the unit, and cap the electrical connections.
2. Why Remove the Tank? (Beyond Emissions)
Aside from fixing the dreaded DEF system faults, removing the physical tank offers tangible benefits for LML owners:
Improved Ground Clearance
The factory tank hangs several inches below the frame rail. If you take your truck off-road, into fields, or over construction site debris, that plastic tank is a liability. Removing it restores the clean, flat underside of the passenger chassis.
Weight Reduction
A full DEF tank holds about 5.3 gallons of fluid. Including the tank assembly, pump, and skid plate, you are carrying nearly 60 to 80 lbs of dead weight on one side of the truck. Dropping the tank balances the truck and sheds unnecessary payload.
3. The Critical Step: Protecting the Harness
This is where "cheap" deletes fail.
When you remove the tank, you will disconnect the main harness that powers the pump, heater, and level sensors.
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The Wrong Way: Wrapping the open plugs in electrical tape. Water will get in, corrode the pins, and potentially short out your BCM (Body Control Module) or cause other electrical gremlins.
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The Right Way: Use a DEF Plug Kit (Dummy Plugs). These are weather-sealed caps that snap onto the factory harness connectors. They keep moisture and dirt out, ensuring that if you ever need to reinstall the system (for resale or inspection), the plugs are factory-fresh.
4. Installation Tips: Dealing with the Straps
Dropping the LML tank can be a wrestle.
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Drain It First: Don’t try to bench press a sloshing tank. Siphon the fluid out first. Warning: DEF fluid is corrosive to paint and concrete. Handle with care.
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The Straps: The tank is held by metal straps similar to a fuel tank. On older 2011–2013 models, the bolts may be rusted. Spray them with penetrant oil the night before.
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The Filler Neck: Don't forget to disconnect the filler neck from inside the fuel door area before you yank on the tank!
Summary: Finish the Job
Don't do a "half-delete" where you disable the system but leave the ugly, heavy hardware hanging under your truck.
A Complete 2011-2016 Duramax DEF Removal clears the codes and clears the chassis. It makes your truck look higher, run lighter, and travel safer off-road.
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