Table of Contents

How EGR Works on the LML

EGR (exhaust gas recirculation) sends a portion of exhaust gas back into the intake to lower combustion temperature and reduce NOx. On the LML, the gas is cooled by liquid-cooled EGR coolers, metered by the EGR valve, and mixed into the intake air. The coolers use engine coolant, so a leak inside a cooler becomes a coolant problem.

What GM Has Documented About EGR Cooler Leaks

GM service bulletin 08-06-04-003C (September 2014) covers 2002 to 2015 Silverado and Sierra trucks with 6.6L Duramax engines, including the LML. It exists because EGR cooler leaks are a known cause of coolant problems on these engines. GM states:

  • Leaks from the EGR cooler may allow coolant to pass through the exhaust system and enter the combustion chambers on the right bank cylinders.
  • Failing to inspect the EGR cooler for leaks may lead to a misdiagnosis of coolant in the combustion chamber.
  • If an investigation of coolant loss leads to coolant found in one or more right bank cylinders, the EGR cooler must be pressure tested before any engine repair is attempted.

GM also supplies dealers with a dedicated adapter set for 2010 to 2011 Duramax engines with the multiple-cooler EGR system. The point for you: confirm the cooler is the problem before you replace parts or open up the engine.

Symptoms That Call for a Shop Visit

  • A coolant level that keeps dropping with no visible external leak.
  • White smoke from the exhaust.
  • Overheating. Do not keep driving on low coolant.
  • EGR codes on a scan tool, such as P0401 (insufficient EGR flow). 

Several parts can cause coolant loss, so a pressure test is how you know. Do not clear codes and keep driving.

What a Complete LML EGR Delete Kit Includes

Important: the parts below are for off-road, race, or non-public-road use where permitted, as set out in the notice at the top of this page.

EngineGo's LML Duramax EGR delete kit listings cover 2011 to 2016 Silverado and Sierra 2500HD and 3500HD trucks. A complete kit should give you:

  • Cooler delete and valve block-off hardware to seal the openings the EGR parts leave behind.
  • Coolant bypass hardware. The coolers are part of the engine's coolant circuit, so flow has to be maintained or sealed correctly. After the work, refill and bleed the cooling system fully.
  • Gaskets for the new connections.
  • A matching tune. The ECM monitors EGR-related inputs, and hardware without a matching calibration will set codes and can put the truck into reduced power. The kit does not include a tune, so pair it with an LML Duramax tuner that lists your model year.

EGR Only or a Full Setup?

An EGR delete does not touch the DPF or DEF systems. Those are separate, and the exhaust side has its own fitment split.

Setup What it covers Tune needed
EGR kit only The EGR cooler and valve Yes
EGR kit plus delete pipe Adds the exhaust section Yes
Full setup EGR, DPF, and DEF hardware Yes

If you add exhaust work, match the pipe to your build date: the LML downpipe uses a V-band clamp from 2011 to 2015 and a three-bolt flange from 2015.5 to 2016. See the LML Duramax delete pipe options, and talk to us before you order so the tune matches the final configuration.

For the full DPF, EGR, and DEF picture, read the LML Duramax delete kit buyer’s guide.

Installation Notes

This is not a beginner job. It involves draining and refilling the cooling system and working around the intake and turbo area. Our LML EGR delete install steps walk through the job.

  • Let the engine cool completely before any cooling system work.
  • Partially drain the coolant before removing the cooler hoses.
  • Bleed the cooling system fully before driving.
  • Wear eye protection and gloves, use jack stands if you lift the truck, and dispose of old coolant properly.
  • Do not guess at torque values. Use the service information for your truck.

If you are not comfortable with cooling system work, have a shop handle it.

FAQs

Will this fit my exact truck?

The kit is listed for 2011 to 2016 Chevy Silverado and GMC Sierra 2500HD and 3500HD trucks with the 6.6L LML Duramax. It is not listed for Cab and Chassis trucks. Check the Vehicle Fit Guide on the product page before ordering, and send us your VIN if you are unsure.

Do I need a tune for an EGR delete?

Yes. The ECM expects EGR hardware, so the hardware and the tune go together.

Will it set a check engine light?

Without a matching calibration, expect codes and possible reduced power. With a proper tune, EGR-related codes are addressed, but the outcome depends on the tune and the truck's condition.

Is an EGR delete legal?

Not for on-road use. Removing or disabling emissions equipment on a vehicle used on public roads violates the federal Clean Air Act and many state laws. An off-road use disclaimer does not change how an EPA-certified vehicle is treated under federal law. Check federal, state, and local rules for your situation before buying or installing anything.