3.0 duramax problem

Wintersun · September 10, 2020

I have had so many problems with my LML Duramax engine that I stopped using it for long trips. With some emissions related problems I could go to 4 different dealers and the problem would not be fixed. Finally found a fifth dealer with a competent mechanic to fix the problems with the first visit.

There are problems with the sensors (NOx, DEF tank, DEF warmer, DEF pump, and with the wiring harness and with the programming that tries to diagnose problems. Three vacation trips in a row had to be cancelled due to emission controls problems. Very few mechanics have any ability to troubleshoot the problems and depend 100% on an error code to know where to start.

Many of the problems are bugs in the code, for example my truck went into limp mode and the error code indicated that the DEF tank was empty when it actually was 100% full. Only option was to drive at 55 mph a couple hundred miles back to my house. Driving on an interstate at 55mph and trying to safely merge with traffic, including the tractor trailer rigs are doing 70mph, is dangerous. I will never own a vehicle that puts myself and my passengers at risk with "limp modes".

jnissen · September 11, 2020

Well what was your root cause if four shops couldn’t fix it?

redwngr · September 11, 2020

17 hours ago, Wintersun said:

I have had so many problems with my LML Duramax engine that I stopped using it for long trips. With some emissions related problems I could go to 4 different dealers and the problem would not be fixed. Finally found a fifth dealer with a competent mechanic to fix the problems with the first visit.

There are problems with the sensors (NOx, DEF tank, DEF warmer, DEF pump, and with the wiring harness and with the programming that tries to diagnose problems. Three vacation trips in a row had to be cancelled due to emission controls problems. Very few mechanics have any ability to troubleshoot the problems and depend 100% on an error code to know where to start.

Many of the problems are bugs in the code, for example my truck went into limp mode and the error code indicated that the DEF tank was empty when it actually was 100% full. Only option was to drive at 55 mph a couple hundred miles back to my house. Driving on an interstate at 55mph and trying to safely merge with traffic, including the tractor trailer rigs are doing 70mph, is dangerous. I will never own a vehicle that puts myself and my passengers at risk with "limp modes".

What year was your LML?

First Time Truck · September 11, 2020

On 8/14/2020 at 8:01 PM, ullose272 said:

Just had my first issue with my truck. Was pulling my trailer for about 2 hours 2000 lbs maybe, and noticed it was cutting out a little here and there. Came to a stop, sat there idleing for maybe 5 min. Then went to go again, all of a sudden, servce ESC light, service park brake light, and service emision system light, reduced power and was cutting out really bad and really bad shudder feeling. Ideas?

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Hi OP,

any updates regarding the issue?

ullose272 · September 11, 2020

Hi OP,

any updates regarding the issue?

Havent heard anything, it was 2 days ago they told me a engineer was coming out, i dont know how long that takes.

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First Time Truck · September 14, 2020

On 9/11/2020 at 5:31 PM, ullose272 said:

Havent heard anything, it was 2 days ago they told me a engineer was coming out, i dont know how long that takes.

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Thanks for the update, I am in a similar situation. 350 or so miles in truck. Got a service transmission, service ESC, traction control, CEL. Dealership called and said maybe an electrical issue. Been there about a week and a half.

ullose272 · September 14, 2020

Thanks for the update, I am in a similar situation. 350 or so miles in truck. Got a service transmission, service ESC, traction control, CEL. Dealership called and said maybe an electrical issue. Been there about a week and a half.

Good luck!

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ullose272 · September 16, 2020

Thanks for the update, I am in a similar situation. 350 or so miles in truck. Got a service transmission, service ESC, traction control, CEL. Dealership called and said maybe an electrical issue. Been there about a week and a half.

Let us know if they figure it out

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First Time Truck · September 17, 2020

On 9/15/2020 at 7:59 PM, ullose272 said:

Let us know if they figure it out

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Picked the truck up yesterday, service manager said they repositioned ground wires. There were multiple codes - P2122, C2a07, u0131, u0151, u0102, u0140, and u0146, they inspected the engine compartment wiring harness for rub through and connector terminal contact per doc 5568637, repositioned harness and secured per doc. They test drive multiple times and codes did not reset.

the drive home from dealership was uneventful as everything seemed to work fine.

jnissen · September 17, 2020

Yeah sounds like assembly issues have not necessarily gone away. I wonder if better positioned strain relief on the harnesses and grounds are needed or just improper assembly to begin with? Did the engineer find this?

Good to hear your up and running again. Better tow with it ASAP to determine if the engine movement will make it return.

ullose272 · September 17, 2020

Picked the truck up yesterday, service manager said they repositioned ground wires. There were multiple codes - P2122, C2a07, u0131, u0151, u0102, u0140, and u0146, they inspected the engine compartment wiring harness for rub through and connector terminal contact per doc 5568637, repositioned harness and secured per doc. They test drive multiple times and codes did not reset.

the drive home from dealership was uneventful as everything seemed to work fine.

Thats awesome, hope its fixed, i guess my dealership is still waiting for the engineer to show up [emoji58]

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Maven · September 17, 2020

Hopefully they fixed it even though after all of your time and issues they couldnt even use the proper service manual document. That doc# you referenced is information for harness chafing on the 2.7turbo. I imagine they found an issue with your harness about a foot and half from the ECM connectors where the engine harness runs over the alternator. That may be where your problem lies as well ullose272, it's been showing up on a few trucks.

ullose272 · September 23, 2020

Update, engineer finally made it today, they spent most the day working on it. Ended up overnighting a engine and injector wiring harness. Hopefully have it back friday

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