2020 3.0 P026A cel

[Grey3liter4x4]

Just wanted to post some information in the event someone with a vehicle similar to mine starts to get engine check lights and a loss of intercooler coolant.  I've had my truck for almost 2 years.  Had the leaking rear slider fixed, a seat belt recall, and the occasional random cel that would pop up and then go away on its own.  I have a scanner and some of the codes were very random but nothing that effected how the truck drove or required a visit to the dealer, until.....6 months ago I get a persistent P026A code.  Code is basically the incoming air charge from the turbo is outside of acceptable parameters.  5 trips to the dealer with a weekly loss of coolant from the intercooler expansion tank the problem was finally figured out. 

 

GM has a service recommendation for the techs to check a possible kinked lower hose on the drivers side that would restrict coolant flow but that was not the problem.  Basically what was happening was the coolant for the intercooler was not flowing into the intercooler from the engine side.  Coolant was getting overheated and over pressurized in the fill tank causing it to blow past the cap, supply hose clamps, and through the overflow tube.  All at different times and only after the truck had been driven hard, highway speeds over 30 mins long, hot days, long hills, etc.  Pressure testing would not duplicate the leak, fill tank was changed, replaced hose clamps, and on and on.  

 

The tech finally figured out that one of the hoses from the intercooler on the passenger side of the engine had a union that was installed backwards at the factory.  The incorrect installation was creating a kink in the hose.  As the coolant expanded the kink would get worse essentially closing off the normal flow of intercooler coolant.  Heated coolant coming off the motor had no where to go but out of the tank.  The kicker is that there is a trim piece that completely covers the hose where the fitting is located.  Unless the tech knows to remove the cover and inspect the hose there is no way to tell there is a problem.  The fitting was removed and flipped around to remove the kink and so far so good.  

 

In all the months of trying to figure out the problem I could not find any reference to a P026A code and a 3.0 duramax.  So hopefully if this is someone else's problem have them check that hose fitting if they can't figure out.  

[MTB]

I’m getting this code very often since we started getting cooler here in Texas. I’m going to look for this issue in the morning. Thanks for your post.

[kkacz]

2021 3.0 duramax code p026a keeps coming on truck performs as should. First trip to dealer they said kink lower hose was the fix. Second trip is intercooler pump bad. Truck is in today getting pump installed.

[kkacz]

Repair sheet from dealer says burnt out intercooler pump from kink in lower hose. Hope this is the fix and light dont come back on.

[jshelley87]

When you were having this issue was your truck running hot? Mine is running at normal temperatures (210-215 degrees F) and I'm not losing coolant.. could it just be the sensor then?

[redwngr]

There are two cooling systems on the 3.0.

 

The big system is for engine cooling and it is the system that sends info to the temp gauge.

 

The smaller system is for the intercooler (cools the air after the turbo and before it enters the engine).

It does not send info to a gauge on the dash.

It is the system with the kinked hose that OP was posting about.