DMAX 3.0 Code P26C0

Phatty · August 14, 2020

Well threw a code... 300 miles from home. I had just dragged my trailer (7500lbs with water)- 280 miles from home mostly on the freeway at 75mph, over several very large mountain passes. I then was hauling the trailer up to a ski resort at 10,000 feet up an 6-18% grade road (https://www.dangerousroads.org/north-america/usa/4005-beaver-canyon-byway.html) for the curious. We had a race we were running up there and wanted a shower and comforts for when we were done.
She was running hot pulling those steep turns and three turns from the top threw the code and went into limp mode. We were there 3 days. we camped a couple of miles from the race start and so after driving back and for a bunch on day 2 i finally got the code to clear with my scanner. Dealership said to leave trailer and limp home. I had no locks and didnt want another weekend shot. I ended up making the drive home late at night (cooler temps) and much lower speeds and limped home. Code never came back on. Truck is at dealer, who says they may not be able to do anything since I cleared the code...

Anybody else get this code yet?

Phatty · September 21, 2020

Well update on p26C0. i cleared the code so I could drive back home. Dealer did nothing about it. It has not come back. They will not fix it unless it throws code.
Took another long camping trip and threw code p0421. It put me into limp mode at 65mph limit after 175 miles ( i was 300 away from home). This time I did not clear it.
Dealer said unless it was "ACTIVE" that they were not authorized to fix it. They cleared it and gave me truck back. A bunch of BS. Keep the code so we can fix it, so I keep the code and they dont fix it.
I cant win. This is getting old. Truck has 8000 miles on it. Beginning to think pulling 7000lb trailers in the rocky mountains is too much for this truck. Whats going to happen on my next long camping trip... stay tuned.

Grover67 · September 21, 2020

Not to impressed when I had mine in for a code and the Def update from it. Got it done and received 3 pages of "stuff" they said they checked and also said they washed it, which they didn't lol. Got it home and rechecked the codes with my scanner and they didn't even clear the codes that were in there when I brought it in, not much confidence from all that....

-Grover67

DemonWorks · September 29, 2020

On 8/14/2020 at 11:55 AM, Phatty said:

Well threw a code... 300 miles from home. I had just dragged my trailer (7500lbs with water)- 280 miles from home mostly on the freeway at 75mph, over several very large mountain passes. I then was hauling the trailer up to a ski resort at 10,000 feet up an 6-18% grade road (https://www.dangerousroads.org/north-america/usa/4005-beaver-canyon-byway.html) for the curious. We had a race we were running up there and wanted a shower and comforts for when we were done.
She was running hot pulling those steep turns and three turns from the top threw the code and went into limp mode. We were there 3 days. we camped a couple of miles from the race start and so after driving back and for a bunch on day 2 i finally got the code to clear with my scanner. Dealership said to leave trailer and limp home. I had no locks and didnt want another weekend shot. I ended up making the drive home late at night (cooler temps) and much lower speeds and limped home. Code never came back on. Truck is at dealer, who says they may not be able to do anything since I cleared the code...

Anybody else get this code yet?

Your dealer failed you and this is concerning. The code is a very important one that needs to be addressed. There is a bulletin for wire rub which they need to check.

If it passes that, they need to look up the code and see what it means. In this case, it's the coolant valve is sticking. This is a huge problem that needs to be fixed before you tow again !

GMCustomerService · October 9, 2020

On 9/21/2020 at 2:58 PM, Phatty said:

Well update on p26C0. i cleared the code so I could drive back home. Dealer did nothing about it. It has not come back. They will not fix it unless it throws code.
Took another long camping trip and threw code p0421. It put me into limp mode at 65mph limit after 175 miles ( i was 300 away from home). This time I did not clear it.
Dealer said unless it was "ACTIVE" that they were not authorized to fix it. They cleared it and gave me truck back. A bunch of BS. Keep the code so we can fix it, so I keep the code and they dont fix it.
I cant win. This is getting old. Truck has 8000 miles on it. Beginning to think pulling 7000lb trailers in the rocky mountains is too much for this truck. Whats going to happen on my next long camping trip... stay tuned.

This is certainly not the sentiment we wish to hear, Phatty. Our team would like to take a closer look into this for you. To do so, please send an email to [email protected] ATTN:Aleigha. Be sure to include your contact information, VIN, and involved dealership. We will be on the lookout for your email. To learn more about GM's privacy policy, please visit http://bit.ly/2h3ZUnC.

Aleigha W.

Edcanez · April 21, 2024

Did you ever get this coolant valve fixed ? I have the same issue

mjm-1957 · April 21, 2024

Everyone made had this issue. We are changing them like crazy and are having a hard time getting them.

Dark Cloud · June 5, 2024

Driving into work yesterday my 2020 Silverado with the 3.0L Duramax lost power and provided code P26C0. I was fortunate enough to limp it into a nearby dealer that I've never gone to. I recieved a call from the service guy a short while ago saying the engine's coolant control valve is stuck closed. The bad news, no parts available, and no eta on when they will be and the truck isn't drivable according to them and I would agree based on the limited - aka reduced power alert.

I don't want to be nasty about things in life, especially those I can't control and I haven't been yet. But I'm absolutely livid over this. This is a damn Chevy truck in the USA, why the hell aren't there enough parts available to build thousands of these truck from scratch if needed? This really forces me to rethink future purchases down the road if this is how GM is going to operate.

Any advise on how to handle would be immensely appreciated.

@GMCustomerService what are my options?

GMCustomerService · June 5, 2024

3 hours ago, Dark Cloud said:

Driving into work yesterday my 2020 Silverado with the 3.0L Duramax lost power and provided code P26C0. I was fortunate enough to limp it into a nearby dealer that I've never gone to. I recieved a call from the service guy a short while ago saying the engine's coolant control valve is stuck closed. The bad news, no parts available, and no eta on when they will be and the truck isn't drivable according to them and I would agree based on the limited - aka reduced power alert.

I don't want to be nasty about things in life, especially those I can't control and I haven't been yet. But I'm absolutely livid over this. This is a damn Chevy truck in the USA, why the hell aren't there enough parts available to build thousands of these truck from scratch if needed? This really forces me to rethink future purchases down the road if this is how GM is going to operate.

Any advise on how to handle would be immensely appreciated.

@GMCustomerService what are my options?

We are sorry to hear of these concerns you are having with your Silverado and would like to investigate this further for you. Please send us an email to [email protected]. Be sure to include your Username and Forum name in the subject line with additional details. We look forward to your email.

mjm-1957 · June 5, 2024

Let them fix it and get out of that truck while it still has some resale value. That is nothing but a disappointment that will only get worse the longer you keep it. They come in all day long with NOX sensor codes,oil consumption problems, oil leaks from the front cover or the rear main seals. The wiring is absolutely the cheapest and thinnest strands of wire they could source to use and then ran it so tightly that it rubs threw on the alternator brackets,motor mounts and on and on. These trucks are a disgrace and thats coming from a GM line mechanic for 49 years. GM should be ashamed to put out trash like that and at that price point. The electronics put in these trucks are far from perfected. Install all the component and ship it. When it comes back, and it will, let the dealer worry about it.Dont even get me started about all the transmission problems that fill in the rest of the day.