All About the Duramax LML | Common Problems & Reliability

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00:31 – Differences Between the Duramax LMM vs LML
02:24 – Duramax LML Common Problem #1 – CP4.2 Injection Pump
05:01 – Duramax LML Common Problem #2 – DEF Heater
06:13 – Duramax LML Common Problem #3 – NOx Sensors
07:24 – Duramax LML Common Problem #4 – DEF Pump
07:57 – Duramax LML Reliability

[devioux]

2015 4x4 LML here, remove all that emissions crap, swap to CP3 and lift pump, it’ll be the best thing you ever did for your truck. She’s currently at 260k and still purrs like a kitten and I have no intentions of letting her go anytime in the foreseeable future.

[joeytaylor]

My def tank and dpf somehow fell off and haven't had any problems since 🤷‍♂️ So weird

[THDC]

Thanks for this video. Very informative. Im on the edge - days away from buying a 2016 GMC 3500hd Denali Duramax with 81k. An unmolested beauty in incredible condition. Replacing my 2009 Sierra which has nearly 600k. Keep up the great work - im a new subscriber!

[lostcreek]

In my local area there is a lml hot shot truck that has almost 500, 000 miles stock.

[jamesclark]

Actually, the DEF heater problem affects all users. If a heater fails, even at temperatures well above freezing, you still end up in limp mode. I know because I had a tank heater fail en-route to Alaska in the Yukon, 130 miles from Whitehorse. The warning appeared on the DIC, and informed me that I had 150 miles to go before I'd be limited to 4 mph. We got back to Whitehorse and spent a week waiting for a new tank (you can't just replace the heater). You'd think the bright bulbs who impose these limits would design a better system, and allow more miles.

[-sv]

I've heard the same thing covered in this video from several sources, so the first thing I did when I bought my 2016 GMC 2500… like within a month…was add a lift pump, do the CP3 conversion and DPF delete.

[フレひ]

Love owning a deleted 2016 LML. By 2016 apparently a lot of the injection issues were fixed so I’ve heard no need for a lift pump

[offical_weaponx]

Looking to buy a 16’ LML 170k already tuned/deleted.they had it 4 years no problem super clean. Shop just did some suspension work and checked the fuel system everything was fine but it’s still on the stock cp4

[husnan]

I love your videos so educational, have you done the same on the Cummins series and power strokes as well ?

[Foxfried]

CP3 with lift pump make the LML the best modern duramax, avoids the injector problems of the L5P and the newer L5P can not even be tuned now.

SO stock LML, Hell no CP4 hell. Modified LML with CP3 + LIFT = the best. Easy 200HP increase on stock with delete.

[Eastcoastweldah]

my lml has 140k. shes deleted and runs like a champ. fingers crossed my truck was built midweek and not on a friday.

[wicked]

The fuel pump on my 2002 Sierra died this week so I had to take it in for replacement. I have a 2015 Sierra LML that I typically don't drive in the winter - I use the 02. Since the 02 is now in the shop, I have to drive the 2015. We've had really low temps (@ 4 days with highs in the minus zero range). The past week it's been in the upper 30's to low/mid 40's. When I started the 2015 it struggled to start - took 5-6 attempts and finally started. However, the "engine" icon lit and has stayed on. There's no message anywhere (I had to have the 2015 DEF system serviced/replaced by a Chevy dealer a couple of years ago under warranty) and at that time I got a message to check the DEF system with the speed reduction notice.

The shop that's working on my 02 doesn't have the ability to read diesel codes if there are any (the 2015 has 48, 000+ miles). I did have it's fuel filter replaced this past summer so probably less than 3, 000 miles on. The nearest dealer that serviced the 2015 for the DEF repair is @ 55 miles away (I drove it there and they gave me a ride back home, then picked me up when the work was done so no complaints there).

The owners manual just says to check the emissions system when this icon lights and stays on. I haven't tried disconnecting the batteries to see if that does anything (a Duramax forum member said that "fixed" his problem). As it's now the weekend I can't contact the dealer until Monday.

Any ideas/suggestions in the meantime?

[towtruckdee]

So delete it. & Cp3 Swap. Got it lets start saving? What would be the price on all these parts? Im not worried about labor.

[lunarlambo]

If you buy a used 2016 how can you tell if it has a CP4 or CP3???

[austinsnodgrass]

Why would you not recommend deleting the entire emissions system if it is going to make your truck that much more reliable?

[patrickr]

do you have any opinions on the crankshaft? I'm looking at buying a 2011 LML with 180, 000 miles, but I've heard some stories of the crank breaking because of the firing order. is this a common issue?

[JoseChavez-znvm]

When replacing cp4 with the cp3 would i have to replace anything else with it or is it a simple remove and replace?

[nicetomeetme]

So far... biggest issues with my lml.. is emmisions. Plan on deleting that.

I had to replace egr bypass, egr valve, egr pipe cracked, for some measure of reliability i replaced egr coolers with aftermarket "Bulletproof".

Idk.. sick of messing with my lml, i want to play with my l5p finally

[MrPaul]

If you’re looking for a used lml and you know your going to delete the emissions at what point do these failures start. Or is it best to look at another year range

[culllivesmatter]

I plan on upgrading from LWN to LML, it’s already on a diet but is there way I can look and see if it already has a cp3?