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Ooops, I posted this on another thread but meant to post it here.

Does anyone know if #17-NA-171 includes 2018's or if there's a similar bulletin for the '18's?? My truck has had some of these symptoms since I bought it, but I just thought it was part of having a new truck with the transmission trying to learn. I have my truck at the dealer right now and he's telling me my tranny is all fucked up and that it doesn't know how to shift because I have 35" tires. My tranny is throwing all sorts of codes right now. He says this is what's causing the horrible mileage with my truck and if they call this into GM to do a relearn, my warranty is going to be voided because I have bigger wheels/tires and there's a lift on the truck.

I can't believe the 35" tires are affecting the transmission shifting properly considering I've had them on 2 previous trucks. Is this something new with a 2018?? He also said they can normally go into the ECM? and modify the tire size to allow the truck to know there are different sized tires on the truck, but they can't do that with the 2018's yet...anyone know anything about this?

They must be digging through all the systems on the truck, they know I changed the headlight bulbs, fog light bulbs, and put LED's in the backup lights...crazy.
 

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I had it done to my ‘17, but it didn’t do much for the transmission. I can’t stand to drive my truck around even empty without tow/haul on because of how weird it shifts. But mine has never thrown any codes.


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I had it done to my ‘17, but it didn’t do much for the transmission. I can’t stand to drive my truck around even empty without tow/haul on because of how weird it shifts. But mine has never thrown any codes.


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See I never really thought mine shifted funny when driving it around empty. What I have noticed is when shifting from park to drive, the truck like lurches and makes a kind of clunk. Then over the Independence Day weekend, the thing shuttered when shifting from 3 to 4 or 4 to 5, not really sure what shift it was but I know it didn't feel right and even made the gf go WTF was that??

Mileage has been at best upper 15 and that was when the truck was stock driving empty. It dropped like 1.5-2 mpg after the lift and wheels and tires, which I expected.
 

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Has anyone seen the P26D, without a snow plow installed? I just purchased a used 2017 L5P with 58K miles, and I have had it in the shop 3 times now. Drove off the lot and 20 miles CEL came on for P026D, they replaced a NOX sensor then 20 miles later a CEL again, the same code and they found 3 or 4 Injectors bad (I don't have the paperwork on me), now 165 miles later in the shop again and waiting the diagnostics. All in 27 days. I love the way the truck looks, and OMG the power!! But if I cant get 200 miles down the road, its gotta go. Need some help please.
 

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I have a 2018 Chevy 2500HD High Country. It is running like crap getting 6 mpg stumbles misses and incredibly hard to start when warm.
Diagnostics are as follows:
The code(s) and explanation(s) associated with this issue is/are:

P01CB The Engine and Transmission System is not performing as expected. An issue has been detected in the Fuel Management System used to maintain, control and monitor fuel consumption. If the check engine light is flashing, a misfire condition has been detected. A misfire increases vehicle emissions and could damage the emission control system on the vehicle. Please reduce vehicle speed, avoid hard accelerations, avoid steep uphill grades, and reduce any cargo loads such as a trailer. If the vehicle is continually driven with the check engine light on, the emission controls might not work as well, the vehicle fuel economy might not be as good, and the engine might not run as smoothly. This could lead to future repairs.

P01CF The Engine and Transmission System is not performing as expected. An issue has been detected in the Fuel Management System used to maintain, control and monitor fuel consumption. If the check engine light is flashing, a misfire condition has been detected. A misfire increases vehicle emissions and could damage the emission control system on the vehicle. Please reduce vehicle speed, avoid hard accelerations, avoid steep uphill grades, and reduce any cargo loads such as a trailer. If the vehicle is continually driven with the check engine light on, the emission controls might not work as well, the vehicle fuel economy might not be as good, and the engine might not run as smoothly. This could lead to future repairs.

P01D1 The Engine and Transmission System is not performing as expected. An issue has been detected in the Fuel Management System used to maintain, control and monitor fuel consumption. If the check engine light is flashing, a misfire condition has been detected. A misfire increases vehicle emissions and could damage the emissihttps://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=23&ved=2ahUKEwjYzM2qja_eAhXxFjQIHXCGA5QQFjAWegQIAxAB&url=http%3A%2F%2Fwww.underhoodservice.com%2Fduramax-dilemma-injector-circuit-diagnostics%2F&usg=AOvVaw0L2LoD_yibREdwUk8wh70lon control system on the vehicle. Please reduce vehicle speed, avoid hard accelerations, avoid steep uphill grades, and reduce any cargo loads such as a trailer. If the vehicle is continually driven with the check engine light on, the emission controls might not work as well, the vehicle fuel economy might not be as good, and the engine might not run as smoothly. This could lead to future repairs.

P01D3 The Engine and Transmission System is not performing as expected. An issue has been detected in the Fuel Management System used to maintain, control and monitor fuel consumption. If the check engine light is flashing, a misfire condition has been detected. A misfire increases vehicle emissions and could damage the emission control system on the vehicle. Please reduce vehicle speed, avoid hard accelerations, avoid steep uphill grades, and reduce any cargo loads such as a trailer. If the vehicle is continually driven with the check engine light on, the emission controls might not work as well, the vehicle fuel economy might not be as good, and the engine might not run as smoothly. This could lead to future repairs.

Based on the results, you should service your Chevrolet within 7 days.

Has any one had similar issues?
Was told there was a service bulletin out telling dealers NOT to work on the problem??? WTF
I now have a $74K piece of junk with only 6,450 miles on it can anyone help or give suggestions?
 

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I know from other vehicles you could try this trick, disconnect both negative cables, turn ignition to on to drain any voltage stored, wait ten minutes reconnect, see if its fixed
 

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I have a 2018 Chevy 2500HD High Country. It is running like crap getting 6 mpg stumbles misses and incredibly hard to start when warm.
Diagnostics are as follows:
The code(s) and explanation(s) associated with this issue is/are:

P01CB The Engine and Transmission System is not performing as expected. An issue has been detected in the Fuel Management System used to maintain, control and monitor fuel consumption. If the check engine light is flashing, a misfire condition has been detected. A misfire increases vehicle emissions and could damage the emission control system on the vehicle. Please reduce vehicle speed, avoid hard accelerations, avoid steep uphill grades, and reduce any cargo loads such as a trailer. If the vehicle is continually driven with the check engine light on, the emission controls might not work as well, the vehicle fuel economy might not be as good, and the engine might not run as smoothly. This could lead to future repairs.

P01CF The Engine and Transmission System is not performing as expected. An issue has been detected in the Fuel Management System used to maintain, control and monitor fuel consumption. If the check engine light is flashing, a misfire condition has been detected. A misfire increases vehicle emissions and could damage the emission control system on the vehicle. Please reduce vehicle speed, avoid hard accelerations, avoid steep uphill grades, and reduce any cargo loads such as a trailer. If the vehicle is continually driven with the check engine light on, the emission controls might not work as well, the vehicle fuel economy might not be as good, and the engine might not run as smoothly. This could lead to future repairs.

P01D1 The Engine and Transmission System is not performing as expected. An issue has been detected in the Fuel Management System used to maintain, control and monitor fuel consumption. If the check engine light is flashing, a misfire condition has been detected. A misfire increases vehicle emissions and could damage the emissihttps://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=23&ved=2ahUKEwjYzM2qja_eAhXxFjQIHXCGA5QQFjAWegQIAxAB&url=http%3A%2F%2Fwww.underhoodservice.com%2Fduramax-dilemma-injector-circuit-diagnostics%2F&usg=AOvVaw0L2LoD_yibREdwUk8wh70lon control system on the vehicle. Please reduce vehicle speed, avoid hard accelerations, avoid steep uphill grades, and reduce any cargo loads such as a trailer. If the vehicle is continually driven with the check engine light on, the emission controls might not work as well, the vehicle fuel economy might not be as good, and the engine might not run as smoothly. This could lead to future repairs.

P01D3 The Engine and Transmission System is not performing as expected. An issue has been detected in the Fuel Management System used to maintain, control and monitor fuel consumption. If the check engine light is flashing, a misfire condition has been detected. A misfire increases vehicle emissions and could damage the emission control system on the vehicle. Please reduce vehicle speed, avoid hard accelerations, avoid steep uphill grades, and reduce any cargo loads such as a trailer. If the vehicle is continually driven with the check engine light on, the emission controls might not work as well, the vehicle fuel economy might not be as good, and the engine might not run as smoothly. This could lead to future repairs.

Based on the results, you should service your Chevrolet within 7 days.

Has any one had similar issues?
Was told there was a service bulletin out telling dealers NOT to work on the problem??? WTF
I now have a $74K piece of junk with only 6,450 miles on it can anyone help or give suggestions?
With all those codes saying "misfire" and the terrible mpg, I'd guess it's an injector problem - but that's just a guess.


Has anyone heard what's going on with the L5P injectors? I keep seeing reports of 1-3 injectors being replaced but no explanation as to what's wrong with them or if they're doing something to remedy the problem. I was planning to buy a 2020 when they come out but as the original owner of an LB7 who is on his 6th set of injectors, I think I may sit this out till they figure it out.
 

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i would but I bought it in Calif. and have since moved to Idaho.
You're in the U.S.A., right? 'dunno;
Warranty is handled by any Chevy Dealer in the country.
You're not limited to the Purchased from Dealer.
 

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You're in the U.S.A., right? 'dunno;
Warranty is handled by any Chevy Dealer in the country.
You're not limited to the Purchased from Dealer.
You're right! I'll give them a little more time If they don't fix it correctly I'll go for the buy back. Case number is at level 4 escalation right now. Whatever that means:help
 

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I have just experienced the low coolant error message this week. I came on two days in a row, then nothing more.
My truck also has a stumble on acceleration occasionally from a 25-35mph roll. That has happened more than a few times and could potentially be a safety issue in the wrong circumstances.
Mine is a 17 GMC 2500 with 14k miles. Otherwise has been a great truck.
 

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Not sure if this is the correct forum thread to post but this just popped up on my GMC homepage. It's a Recall Notice for the Diesel Engine Heater Block Cord. There is no remedy yet apparently.

GM Recall #:N182206311
NHTSA #TBD
Date Issued:May 01, 2019

Recall Title:

Diesel Engine Block Heater Cord

Recall Description:

General Motors has notified the National Highway Traffic Safety Administration (NHTSA) about an upcoming safety recall that involves customer owned 2017 - 2019 model year Chevrolet Silverado 2500/3500, 2017 – 2019 GMC Sierra 2500/3500, and 2019 Chevrolet Silverado Medium Duty 4500/5500/6500 vehicles. In vehicles equipped with the Duramax diesel 6.6 liter engine and the optional engine-block heater cord, a short-circuit condition may develop in the engine-block heater cable or in the terminals that connect the heater cable to the block heater. A short-circuit condition can cause damage to engine components and, in rare cases, start a fire in the engine compartment. GM is developing a final repair that will restore the functionality of the engine-block heater

Safety Risk Description:

A short-circuit condition can cause damage to engine components and, in rare cases, start a fire in the engine compartment.

Repair Description:

Parts are not currently available, but when parts are available, a bulletin will be published

Recall Status: INCOMPLETE. REMEDY NOT YET AVAILABLE
 

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Same here, on my 2018 2500 GMC, immediately after my 18,000 service the fuel efficiency dropped. All services including new fuel & air filters. Runs okay no leaks under truck. Dealer did not seem to care, says we will check on next service. Was getting 22-23 MPG before service now lucky to get 18 MPG not towing anything. Towing 9,000 pound boat around flat Florida always got around 11 MPG, surprised this light load cut fuel in half.
Any ideas?
 

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Same here, on my 2018 2500 GMC, immediately after my 18,000 service the fuel efficiency dropped. All services including new fuel & air filters. Runs okay no leaks under truck. Dealer did not seem to care, says we will check on next service. Was getting 22-23 MPG before service now lucky to get 18 MPG not towing anything. Towing 9,000 pound boat around flat Florida always got around 11 MPG, surprised this light load cut fuel in half.
Any ideas?
The best I ever got with my truck was low 19's with summer blend. In the winter I'm lucky to see 18.
 
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