idle above 800 ... a pain in traffic

[kjensen]

My 2017 L5P in a GMC 3500 has developed an unususaly fast idle. It is above 800 and is a real pain in traffic. Previously was around 500. After dealership test drive they said " ran ok for me". Anyone have a similar problem.

 

[clrussell]

Regen?

 

[2004LB7]

What does the ECM thinks the ECT is?

 

[TheBac]

Moved to L5P section

 

[Lifted L5P]

Probably in regen ... my 2019 L5P increases the idle 300 rpm when in regen.