Does This Guide Fit Your Truck?
The basics apply to any diesel truck with a cooled EGR system. The failure details below come from manufacturer documents for these engines:
- 2011 and newer 6.7L Power Stroke (Ford F-250 through F-550 Super Duty)
- 2008 to 2010 6.4L Power Stroke
- 6.6L Duramax, including the LMM and LML (GM bulletin covers 2002 to 2015)
This is not a repair manual. Cooler location, plumbing, and parts differ by engine and year, so confirm your engine code and build date before you order anything.
What an EGR Cooler Is
An EGR cooler is a heat exchanger. Hot exhaust gas passes through one side. Engine coolant passes through the other. The coolant pulls heat out of the exhaust before that exhaust goes back into the intake.
The cooler is not the EGR valve. The valve controls how much exhaust flows. The cooler cools it. They are separate parts that sit in different places on the engine and can fail in different ways.
Why Diesels Have One
EGR stands for exhaust gas recirculation. The system sends a portion of the exhaust back into the intake to lower combustion temperature and reduce NOx. The EPA explains why that matters: ground-level ozone forms from chemical reactions between oxides of nitrogen (NOx) and volatile organic compounds.
The cooler is the part that takes heat out of the recirculated exhaust. It ties the exhaust system and the cooling system together, which is why a problem in one can show up in the other.
Where the Cooler Sits on Ford and GM Diesels
6.7L Power Stroke. Ford's workshop description places the EGR cooler on the right (passenger) side of the engine, with the EGR valve and its motor at the right front. Ford also describes two separate cooling systems on this engine. The secondary low-temperature system cools the charge air cooler, fuel cooler, EGR cooler, and transmission oil cooler, and it has its own radiator, pump, thermostats, and degas bottle. If you are losing coolant, find out which degas bottle is dropping.
6.4L Power Stroke. This engine uses one EGR system with two shell-and-tube coolers in series. Ford puts an EGR oxidation catalyst ahead of them to reduce lacquer formation, which protects the coolers. Ford also warns that a blocked deaeration port or hose can damage the EGR coolers and the EGR valve.
Other engines. Location varies. Your service manual shows the exact position for your truck.
How EGR Coolers Fail: What Ford and GM Have Documented
The manufacturer documents we reviewed describe two kinds of failure.
Plugging. Ford Customer Satisfaction Program 21M04 states that the 6.7L Power Stroke EGR cooler can become plugged with hydrocarbon or soot at high mileage. Ford Technical Service Bulletin 13-6-5 ties a check engine light with P0401 to a restricted cooler core. On the 6.4L, Ford's stated reason for the oxidation catalyst is to reduce lacquer in the EGR system.
Leaking. GM service bulletin 08-06-04-003C covers 6.6L Duramax engines. It states that a leaking EGR cooler can let coolant pass through the exhaust and into the combustion chambers on the right bank.
These are different problems with different symptoms. The Ford documents describe plugging. The GM bulletin describes leaking. Neither one says every cooler on every engine will fail.
Signs Your EGR Cooler Needs to Be Checked
- A check engine light with EGR codes. On the 6.7L Power Stroke, Ford's bulletin starts with P0401 and uses P2457 from the key on, engine running (KOER) self test to confirm the cooler. Our P0401 guide covers the code in detail.
- Coolant level that keeps dropping with no visible external leak. On the Duramax, GM's bulletin addresses exactly this kind of coolant loss investigation.
Neither sign proves the cooler is bad. P0401 alone does not confirm it. Test first.
Diagnose Before You Buy Parts
Both manufacturers put a test ahead of the parts order.
- Ford, 6.7L Power Stroke: a technician checks stored codes with a scan tool and confirms there are no other EGR system codes. Then the tech runs the key on, engine running (KOER) self test. In Ford's CSP 21M04 procedure, if both P0401 and P2457 show up, the cooler gets replaced. If only one shows up, the tech runs a pinpoint test and replaces the cooler only if the core is found plugged or fouled. For 2011 to 2012 trucks, TSB 13-6-5 has the same logic: P0401 first, then the KOER test, and the cooler core is replaced if P2457 appears. If the codes do not fit, the program does not apply and the concern goes through further diagnosis.
- GM, 6.6L Duramax: if an investigation of coolant loss finds coolant in one or more right bank cylinders, GM says you must test the EGR cooler for leakage before attempting any engine repair. Which cylinders are affected depends on which exhaust valves were open when the engine was shut off. GM says skipping the test can lead to a misdiagnosis. The test uses GM's EN-48974 adapter set, which shipped to dealers in December 2007. A technician partially drains the coolant, plugs the cooler hoses with the adapters, pressurizes the cooler to 42 psi, then closes the shutoff valve and watches the gauge for pressure decay for 5 minutes.
If the cooler holds pressure, the leak is somewhere else, and a replacement cooler or a delete kit will not fix a problem you do not have. Ask the shop to run these checks and show you the result.
Check Your Coverage First
- Ford CSP 21M04 covers certain 2011 to 2014 6.7L Super Duty trucks built at the Kentucky Truck Plant from November 3, 2009 through March 14, 2014. It provided a no-cost cooler repair when P0401 and/or P2457 were stored, for 11 years or 120,000 miles from the warranty start date, whichever came first. Coverage transfers automatically to later owners. Trucks already past those limits when the program started in January 2022 were eligible through January 31, 2023, and that date has passed. Ask a Ford dealer to check your VIN for any remaining coverage.
- Federal emissions warranty. The federal emissions warranty rule, 40 CFR 85.2103, was revised in 2024. The current text lists components related to exhaust gas recirculation on compression-ignition engines among the major emission control components that carry an 8 year or 80,000 mile warranty. Which model years that revision applies to is something to confirm with your dealer, because older trucks are covered by the emissions warranty printed in your booklet. Read the booklet, then ask the dealer in writing whether the cooler is covered.
If the Cooler Is the Problem
If testing points to the cooler, a dealer or qualified diesel shop can replace it. Ask for the cooling system to be inspected at the same time, since the cooler depends on healthy coolant flow.
Dedicated off-road and race builds sometimes use an EGR delete kit instead. Some EGR kits remove the cooler as well as the valve, and some require a tune so the PCM does not command EGR or flag hardware that is no longer installed. Read the product page for what is included and whether a tuner is needed.
Important: EGR delete kits and delete tuners are intended only for off-road, race, or non-public-road use where permitted. Removing or disabling emissions equipment on a vehicle used on public roads violates Section 203 of the federal Clean Air Act and many state laws. An off-road label does not change how an EPA-certified vehicle is treated under federal law. Check federal, state, and local laws before purchase, and professional installation is recommended where appropriate. Customers are responsible for legal compliance.
Before You Order Anything
- Confirm the engine code, model year, and build date. Parts do not interchange across generations.
- Confirm the cooler is the cause with the KOER self test or a pressure test, depending on your engine.
- Check whether the repair is still covered under Ford CSP 21M04 or your emissions warranty.
- Read what a kit includes and whether it needs a tune.
- Decide whether the truck is a dedicated off-road build, and check the laws that apply to you.
For a platform-specific walkthrough, start with our 6.7 Powerstroke EGR problems guide. If you are comparing hardware across Power Stroke, Cummins, and Duramax, the EGR delete kit buyer's guide lays out the options.
Frequently Asked Questions
Is the EGR cooler the same as the EGR valve?
No. The valve controls how much exhaust enters the intake. The cooler removes heat from that exhaust using engine coolant. They are separate parts and fail separately.
Does P0401 mean my EGR cooler is bad?
Not by itself. Ford's bulletin has a technician run the KOER self test first. P2457 is the code that points to the cooler. If it does not appear, other causes get checked.
Can a leaking EGR cooler put coolant in the cylinders?
GM says it can. Bulletin 08-06-04-003C states that a leaking cooler may allow coolant to pass through the exhaust and into the combustion chambers on the right bank cylinders of the 6.6L Duramax. It also says to test the cooler for leakage before any engine repair, so a head gasket is not blamed for a cooler leak.
Is a failed EGR cooler covered by warranty?
It may be. Ford CSP 21M04 covered certain 2011 to 2014 6.7L trucks for 11 years or 120,000 miles from the warranty start date, and the extended window ended January 31, 2023 for trucks that were already past those limits. Your emissions warranty may also apply, depending on your model year and what your booklet lists. Have a dealer check your VIN and your coverage in writing.
Do I need a tune with an EGR delete?
Yes. The PCM has to be recalibrated so it does not command EGR or flag hardware that is no longer installed. Running a kit without a matching tune sets codes.
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. Check federal, state, and local rules for your situation before buying or installing anything.
Next Step
Send us your year, engine, VIN, and build date, and tell us whether the truck is a dedicated off-road build. We will confirm which parts fit before you order. You can also browse the EGR delete kit collection and review each product's fitment notes and what is included before checkout.
