Received message today 171 miles until speed reduced to 65mph with 5,395 miles on my 2021 GMC Sierra Denali 3.0 Diesel.
- Thread starter Eastwood
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- #22
This nice to know because I plan on running out the old DEF fluid before adding any more.
Oceandiver
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- Apr 9, 2022
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I was under the impression that the alarm (speed limitiing) and DEF level are unrelated. There is a separate alarm for DEF level, independent of the speed limiting alarm.
- Thread starter
- #24
This nice to know because I plan on running out the old DEF fluid before adding any more.
If the DEF low warnings are ignored and the DEF tank becomes empty, the DIC will display messages that describe the action needed and distance until vehicle speed is limited. For the DEF warning light symbol. This came out of my diesel supplement manual for my 3.0 diesel.
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- #26
If these warnings are ignored and driving continues, maximum speed will be limited further when each of the following counters reaches zero.
• 500 Miles to 65 mph Max Speed • 75 Miles to 55 mph Max Speed • 75 Miles to 5 mph Max Speed
We bought a pre-owned 2020 Silverado with the 3.0 Duramax with 26k miles. Still under factory warranty. Have had the DEF warning about “174 mi until power reduced to 65 mph” pop up three different times but no engine light and DEF is showing 35% to 95% full). Had the dealer look into it when it was in for other problems (bad trans, then crankshaft position sensor) but received no info from dealers (2 different dealers).
My stepson says that he has heard that the problem is with the Blue DEF brand DEF being run in GM engines in the Southwest U.S. (Southern CA, AZ, NM, and western TX). Probably has to do with hot dry climate. The issue seems to be that the Blue DEF brand “calcifies” on the insides of the tank and coats the sensors and clogs the nozzle. He had his DEF system replaced (warranty) and has switched to Autozone and Walmart “house” brand DEF. He says he hasn’t had a problem since. He also said there is some kind of litigation going on about the problem.
Now that my truck is in for the third time for yet more warranty work (codes seem to indicate high pressure fuel system, and internal communications network), hopefully this GMC dealer (we’re stranded in Prescott, AZ) will also check into the DEF problem.
My stepson says that he has heard that the problem is with the Blue DEF brand DEF being run in GM engines in the Southwest U.S. (Southern CA, AZ, NM, and western TX). Probably has to do with hot dry climate. The issue seems to be that the Blue DEF brand “calcifies” on the insides of the tank and coats the sensors and clogs the nozzle. He had his DEF system replaced (warranty) and has switched to Autozone and Walmart “house” brand DEF. He says he hasn’t had a problem since. He also said there is some kind of litigation going on about the problem.
Now that my truck is in for the third time for yet more warranty work (codes seem to indicate high pressure fuel system, and internal communications network), hopefully this GMC dealer (we’re stranded in Prescott, AZ) will also check into the DEF problem.
Oceandiver
New member
- Apr 9, 2022
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It's not the Blue DEF in the Southwest. Mine was in three dealerships between NY and Indiana with the exact same issue. At the third visit, after the truck sat in the dealership for 6 weeks, I traded it for a gasser. Do the math, especially with diesel prices going back up, the economics of running the diesel don't add up (I think I calculated I would save $14.00 on a 800 mile trip). Bite the bullet and sell the truck while it's still under warranty. I can't imagine what my repair costs would have been had the truck not been under warranty.
I have a friend who bought the 3.0, here in NY, and he is having the exact same problem.
I really miss the benefits of the diesel (range, power, the "cool" aspect), but the exposure to repair costs just isn't worth it. And with the oil pump maintenance due at 120,000(?) I am afraid the worst of this engine is yet to come.
I have a friend who bought the 3.0, here in NY, and he is having the exact same problem.
I really miss the benefits of the diesel (range, power, the "cool" aspect), but the exposure to repair costs just isn't worth it. And with the oil pump maintenance due at 120,000(?) I am afraid the worst of this engine is yet to come.
Oceandiver
New member
- Apr 9, 2022
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Mooseman, my experience occurred on my second 3.0. I drove the first one 50,000 miles and because the trade in values were so good, I just traded a 2020 for a new 2021...everything went south on the 2021. Lemon yes, but when it happened to a friend also, and I read through all these posts, it just isn't worth the risk of hanging on to it.
Dealer found possible cause of spurious codes.
Got the truck back today. Since there were so many P codes (some were a little out in left field) and that there were several U codes (vehicle communication network), and the DEF DIC indication that happened at the same time, they zeroed in on the possibility that the powered running board system (3rd party system installed by previous owner that plugs into the OBD2 plug) has some shorted, grounded, or open leads and was “sending” random bits into the network (garbage in, garbage out). They could not reproduce the faults with the running boards disconnected. They recommended that we keep the running boards disconnected for a week or so and see if “real” codes get thrown or something doesn’t run right. If it’s clean, plug the running boards back in (after examining all the running board wiring) and see if codes start happening again. We’ll be heading home with the TT tomorrow and see what happens.
Got the truck back today. Since there were so many P codes (some were a little out in left field) and that there were several U codes (vehicle communication network), and the DEF DIC indication that happened at the same time, they zeroed in on the possibility that the powered running board system (3rd party system installed by previous owner that plugs into the OBD2 plug) has some shorted, grounded, or open leads and was “sending” random bits into the network (garbage in, garbage out). They could not reproduce the faults with the running boards disconnected. They recommended that we keep the running boards disconnected for a week or so and see if “real” codes get thrown or something doesn’t run right. If it’s clean, plug the running boards back in (after examining all the running board wiring) and see if codes start happening again. We’ll be heading home with the TT tomorrow and see what happens.
Sorry, don’t remember the brand (truck came with them).
Update:
Headed home with running boards disconnected. Pulling TT, 55 mph, 7th gear, 1800 rpm, cruise control, tow-haul mode, slight grade on interstate, registering about 14 mpg (truck isn’t working too hard). Slight drop in power and mileage (12 mpg) for 10-15 seconds, than trans slams into 6th (as indicated by 300 rpm increase), then immediately shifts smoothly back into 7th (300 rpm decrease). Stopped and checked OBD codes. Only one (P0336 Crankshaft Position Sensor Performance). Continued on towards home. Same thing happened two more times. It then happend a fourth time with all kinds of warnings on the DIC (“Service emissions”, “174 miles before 65 mph max”, “Limiting power to 40 mph”, “Power steering assist deactivated”, the engine stopped, “Put in neutral to restart engine” (interesting since I was now coasting at 30 mph with flashers on, trying to make an unpowered right lane change in front of several 18-wheelers in order to get onto the shoulder, and would have to apply the brake in order to restart). I put it in neutral, hit the start button, all the instrument lights and information displays turned off. Putting it in neutral did help increase the coasting distance. After I coasted safely off the road, I checked the codes.
P0336 CS pos sensor perf
P0087 Fuel Rail Low Pressure
P0700 Trans Control Module
P228A-B Fuel pressure regulators 1-2 force engine shutdown
U0073 CAN bus Communication
U0074 Ctrl mod comm bus B off
U0076 Ctrl mod comm bus D off
U0129 lost comm with brake system control module
U029D-E lost comm with NOx sensor 1-2 module
U02A1 (no definition in reader)
U0100 lost comm with ECM
Was able to continue home. Didn’t use cruise control, used 5th and 6th gears. Took it to dealer. They had GM field tech look into it. Based on others vehicle problems and solutions, they are going to replace the engine wiring harness. Should be ready in a week. We’ll see what happens.
Update:
Headed home with running boards disconnected. Pulling TT, 55 mph, 7th gear, 1800 rpm, cruise control, tow-haul mode, slight grade on interstate, registering about 14 mpg (truck isn’t working too hard). Slight drop in power and mileage (12 mpg) for 10-15 seconds, than trans slams into 6th (as indicated by 300 rpm increase), then immediately shifts smoothly back into 7th (300 rpm decrease). Stopped and checked OBD codes. Only one (P0336 Crankshaft Position Sensor Performance). Continued on towards home. Same thing happened two more times. It then happend a fourth time with all kinds of warnings on the DIC (“Service emissions”, “174 miles before 65 mph max”, “Limiting power to 40 mph”, “Power steering assist deactivated”, the engine stopped, “Put in neutral to restart engine” (interesting since I was now coasting at 30 mph with flashers on, trying to make an unpowered right lane change in front of several 18-wheelers in order to get onto the shoulder, and would have to apply the brake in order to restart). I put it in neutral, hit the start button, all the instrument lights and information displays turned off. Putting it in neutral did help increase the coasting distance. After I coasted safely off the road, I checked the codes.
P0336 CS pos sensor perf
P0087 Fuel Rail Low Pressure
P0700 Trans Control Module
P228A-B Fuel pressure regulators 1-2 force engine shutdown
U0073 CAN bus Communication
U0074 Ctrl mod comm bus B off
U0076 Ctrl mod comm bus D off
U0129 lost comm with brake system control module
U029D-E lost comm with NOx sensor 1-2 module
U02A1 (no definition in reader)
U0100 lost comm with ECM
Was able to continue home. Didn’t use cruise control, used 5th and 6th gears. Took it to dealer. They had GM field tech look into it. Based on others vehicle problems and solutions, they are going to replace the engine wiring harness. Should be ready in a week. We’ll see what happens.
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One thing I’ve noticed in many posts in this thread and my own experience is the “17x miles before 65 mph max” message that we’re wanting to jump to the conclusion (assume) that it’s attributed to low DEF level (maybe because we read about a similar message sequence that was related to DEF in the manual). In my case, every time the 65 mph message has come up, it has been accompanied by another message “Service Emmisions System”. Could this message actually be related to something else in the emissions systems like maybe the soot filter burnoff “regen” system (exhaust pressure sensors, diesel “afterburner” injector, something else)? I also find it interesting that these warnings start with “17x miles” not the “500 miles” that the manual says for the low DEF level.
Just food for thought.
Just food for thought.
Had the same issue on my 2021 AT4 3.0 IL 6. Engine light and reduced speed warning. Engine light would go on then disappear. Short story is after several reprograms by dealership, no more issues with at but was left with a long starting problem. At 50,000 miles they had to replace my transmission. At 55,000 had three major oil leaks show up. Rear main seal, timing chain cover and oil pan seal. About 70 days of lost time between all the repairs. Filed lemon law suit.
Oceandiver
New member
- Apr 9, 2022
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dkboyd,
I just traded mine in for a gasser last year (see above, pure anguish). Should have gone the law suit route. Don't hesitate to get in touch if I can help with my 3.0 experience.
I’m curious to know, did you have issues with your truck pretty much since day 1 or no?
Thanks. Should’ve gone with
no not day one but after about 6 months or so
MyDefectiveGMC
New member
- Sep 9, 2022
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I am having the same issue. 2020 AT4 since Feb of 2022 28000 miles my truck has been in the shop for 97 day's. They have replaced my entire DEF system, transmission after replacing multiple modules. Crankshaft sensor. Still not fixing the shuttering problem. Now they've had it for another month trying to rewire the 12 volt crankshaft sensor system. I am so done with GMC and I am a life long owner and Chevy legend. They gave me a Colorado for a loner. What a horrible vehicle. I'm embarrassed. GM made this truck