Holy Crap! One week after fixing the thermostat in the GMC Envoy that we own, my wife comes home from one of our kids birthday parties, hands me the keys, and tells me the Check Engine Light is on again. Of course I’m thinking it’s going to be the same code that I changed the thermostat for, so I immediately start getting concerned that my repair did not solve the problem. I quickly finished what I was working on with the Monte Carlo and went to work.
I hooked up my code reader to the truck, and to my relief find that the error code is something completely different. It is error P0506! Not that I like getting Check Engine Lights on the truck but at least it was not the same problem!
I do some quick googleing and find out that I can probably fix the issue without buying anything, unless of course it’s a computer issue or an internal engine problem. Barring those two completely disastrous possibilities, the following is what I did to solve the issue.
The first thing I checked was the PVC system. There’s not much to it on the GMC Envoy, it’s just the one Crankcase ventilation port that vents through the rubber hose to the plastic intake thing (I have no idea what that plastic piece is called). I just made sure that all the passages were clear and there were no blockages in the hose or in the path of the intake to the throttle body.
Check The Circled Area For Blockages
Make Sure The Hose Has No Blockages Either
Next I removed the cover over the air filter, there are 3 screws that hold it over the air filter that are in the locations circled in red. The one screw on top is visible, the one of the right is under that hose, and the one on the lower left is down in between the firewall and that nook that is shaped out of the cover. The air filter looked a little dirty where it pulls the outside air in so I turned it to show a cleaner side to the intake area. Other than that you just want to make sure that the air passages are clear and unobstructed.
Remove The 3 Screws Located At The Circled Locations
The Circled Area Is The Air Intake For The Air Filter Box, Make Sure It Is Clear.
Make Sure There Are No Obstructions To The Air Path.
Once I made sure there were no obstructions, I went to looking for vacuum leaks. There are not a lot of vacuum hoses on the Envoy so I didn’t even check them. I went right to what I thought the most probably issue was. The Intake manifold bolts coming loose and causing a massive vacuum leak at the intake manifold seal. Sure enough, I was able to tighten 4 out of the six bolts significantly and the other two a little bit. The bolts are in the locations that are indicated by the circles in the picture. I believe that this is what solved my particular issue….
The Intake Manifold Bolts Are Very Close To The Locations Circled. They Are In Between The Runners, But Accessible After The BCM Is Removed.
I then made sure that the throttle body was clean. I took some throttle body cleaner and sprayed it on and around the throttle body plate to make sure that it was clean. There was a little bit of dirt that came out but nothing that would make me concerned about functionality. At this point it was just a precaution.
Spray Some Throttle Body Cleaner At The Butterfly And Around The Edges Of It.
I then cleared the code on the truck and drove it. So far so good.
So to recap, if you get the P0506 error code on the GMC Envoy or any other 4.2 Liter Vortec equipped vehicle, the most likely issues are:
- A restriction in the air intake system
- A blockage in the PCV system
- A Vacuum leak
- A dirty throttle body
- A bad computer
- An internal engine problem
Fortunately, I was able to fix this issue without spending any money. Most likely you will be able to as well, just follow the steps above and hopefully you will find your issue and fix the check engine light.