So I got my H3 at the end of June this year. I've put an Airaid CAI and Gibson exhaust on it. That and about 5200 miles. Last Sunday I hope in and the check engine light dings to life. Well, I have OnStar so I hit the pretty little blue button for a little diagnostic help. All they could tell me was that it was an exhaust issue that may reset itself after some freeway driving. Well, on my way home Monday morning it did not reset at all. Instead I was stuck going no more than 60 miles an hour on the flats and down to about 45 on any kind of up hill climb. To say it was a lack of power is an understatement.

So I call the dealer and take it in a few days later. Jury duty kept me from getting there any sooner. The diagnosis? A plugged catalytic convertor. Now how that happens in 5000 miles I don't know, but it did. I am supposed to get my baby back today, fingers crossed. My question is, how much better is she going to run now. I never thought there was a serious power problem. Granted, it could always use more, but I'm thinking it should be a lot better now. Afterall, the CC couldn't be plugged over night sitting in a parking lot. I'm assuming it was something that built up over time. Does anybody have any experience with this?

 

What kind of gas are you using?

 

87 octane from Mobil stations.

 

The CC could have collapsed internally..Material defect...Not the first one I heard of doing this..and your aftermarket Intake and or exhaust I can assure you did not cause this.

 

CC's are notorious for this type of failure, don't take much for the brick inside to crack and once it does it's done. Did you hear a rattle when you started the truck? Thats normally the first sign of trouble.

 

I have an update. Friday afternoon the dealership called me. Apparently the CC wasn't the problem or the cause I should say. The exhaust manifold blew causing some baffle material to fall into the CC plugging it. As the repair guy told me, they have never heard of this happening on an H3 before and they apologized for not catching it sooner. Long story short, I am going on a week without the Hummer. They gave me a Trailblazer to drive which isn't terrible, but it's not my truck either. Supposedly it should be done today. Fingers crossed.

 

So, a month later, and the H3 is on its way back in. This time the stabilitrak system is on the fritz. I have a list of other things I want looked at too. One of which is my mileage. Since the manifold was replace I went from averaging about 16 mpg down to just barely 14. Ouch, that is a big hit if you ask me and a far cry from the 20 mpg they advertise.

To top it off, the dealership is over an hour away. Yeah, these once a month trips are getting a bit old. I'm thinking now that when the lease is up, another Hummer will not be in my future.

 

Sucks to hear all you guys having issues with the H3's

 

that sucks, but I'd kill for your mileage Ask them why I am getting 8.5 mpg

as far as the mileage they advertise...that is an EPA estimate...not hummer. All it is is an estimate in perfect conditions and no car will ever hit it consistantly..if ever.

for the other concerns, it sounds like your dealer dropped the ball on the misdiagnosis of the CC....not really GM hummers fault that your dealer sucks...might want to change dealers, I have to do the same thing.

Sorry you feel like you want a different truck when your lease is up...but anytime you buy a first model year production vehicle you have to expect small things to go wrong, just the nature of the beast.

 

I shudder at the thought of 8.5 mpg again .. hell, my H2 does better than that LOL!