What is this hose?

[cybertek]

Since my last service at the GMC dealership I have been getting an occasional "Tighten Gas Cap" message. This morning I went to check the evap selenoid under the hood and foud this hose disconnected.

What is this hose for and could it have be the reason for the "Tighten Gas Cap" message?

Thanks!

 

[Scottydoggs]

thats a evap line. put it back on. likely cause the cap message as its a large evap leak. engine should run smoother too once its back on there.

 

[cybertek]

Thanks!

Yea I put it back on and it definitely runs smoother!

It's very questionable why it was disconnected...

 

[iamdub]

Since my last service at the GMC dealership I have been getting an occasional "Tighten Gas Cap" message. This morning I went to check the evap selenoid under the hood and foud this hose disconnected.

What is this hose for and could it have be the reason for the "Tighten Gas Cap" message?

Thanks!

View attachment 353029View attachment 353030

That's not EVAP, that's PCV. It's the fresh air inlet ("clean side"). The engine inhales filtered air from the throttle body, through the passenger side rocker cover and head then into the crankcase. The vacuum side is the port on the rear of the driver side rocker cover that sucks the PCV fumes outta the crankcase, through the driver side head and into the port at the top center of the intake manifold.

That hose being disconnected would cause a vacuum leak and unmetered air going into the engine, which causes the rough operation and rich or lean exhaust.

 

[iamdub]

Thanks!

Yea I put it back on and it definitely runs smoother!

It's very questionable why it was disconnected...

What service did the dealer perform?

 

[cybertek]

Steering gearbox replacement and steering wheel position sensor replacement. Nothing near that hose.

 

[alpha_omega]

When doing the Gearbox they will often go by the manual and pull the wiring harnesses and disconnect that hose in the process. How they didn’t catch it running like hell or the codes is baffling.

 

[Doubeleive]

exactly why I always look under the hood anytime I pick up my vehicle from being worked on, I have found tools, things disconnected, wire harness not secured, engine cover was missing once, now it's just a habit. Only takes a second for someone to be distracted and to forget to do something.