P20B9 DEF Heater Failure, workaround for limp mode?

[Michael Butts]

Hello,
2020 Chevy Silverado 2500 with 50,315 miles. I'm about 550 miles from home towing a 14,000 lb. fifth wheel.
It's currently showing 86 miles until a derate to 65 MPH.
A. How many miles do I have before I can walk faster than the truck can drive?
B. Is there a temporary way around limp mode?
Thanks!

[newdude]

6 minutes ago, Michael Butts said:

Hello,
2020 Chevy Silverado 2500 with 50,315 miles. I'm about 550 miles from home towing a 14,000 lb. fifth wheel.
It's currently showing 86 miles until a derate to 65 MPH.
A. How many miles do I have before I can walk faster than the truck can drive?
B. Is there a temporary way around limp mode?
Thanks!

 

 

You can try to do a tamper test with a scan tool which "might" clear the limp mode. 

 

But. 

 

Otherwise you gotta fix it.  

[ArrowsmithPML]

You will be walking sooner than you think.

 

You either fix (in some cases there is a warranty issue) or you rip it out and potentially get into other issues.

[Michael Butts]

Well, crap.  I kind of figured I was stuck on this especially since I'm traveling, don't have a full tool kit, and am on a strict schedule.

I found a diesel shop nearby the campground.  I'm hoping they can cram me into the schedule tomorrow!

Thanks for the replies!

[Michael Butts]

I'm running into a 2-4 week wait for diesel shops.  Does anyone know if I purchase an Autel 808 tablet if I can reset the code so I can get back home?

[newdude]

8 minutes ago, Michael Butts said:

I'm running into a 2-4 week wait for diesel shops.  Does anyone know if I purchase an Autel 808 tablet if I can reset the code so I can get back home?

 

 

They won't just clear.  You have to run a tamper test to try and clear the code.  If it has warmed up enough where it won't need to actually use the DEF heater it "should" get through the tamper test.  

[redwngr]

I wonder how OP made out?

 

When it does get to empty, it starts a 500 mile (actual miles, to the def remaining estimator) countdown until it limits speed to 65 mph, then another timer to the next limit --iirc it's 55mph for 175 miles (or something like that) then the 5mph limiter.

 

He said he had 550 miles to go. 

If the 86 til empty was correct he made it before the 65 mph limit started.

If it decided it was empty one mile later, then he had 500 miles at 65 followed by 49 or 50 at 55 mph. 

 

I wanted to confirm how it worked, and wanted to know how much def I could add if it thought it was empty.

So, I intentionally drove my '18 L5P to empty. (I've done this with a 3.0L too)

The 500 mile countdown takes over the dic message area and cannot be cleared.

They do  countdown 1 mile for every mile driven.

I ran about 60 miles watching/testing with the L5P. (only about 2 miles on the 3.0 to get to the metered bulk def location I use) 

 

They display 2 alternating screens.

This is the 2018

 

Alternating with

 

 

I thought I had, but can't find, pics during the countdown before it got refilled.

 

[mjm-1957]

This is why I bought a 2500HD with spark plugs. You can keep those unreliable troublesome pieces of ******.