In November I took my 08 Suburban to a local dealer for a check engine light. I also noticed a small hole in back of muffler with some rust around it. I enquired about the hole as I'm not a mechanic. The dealer said the code for the light was PO121 for a sticking throttle body. They replaced the throttle body for $405 and educated me on the weep hole in the muffler. Now I know. Within two weeks I had a check engine light intermittenly. One time the check fuel cap warning came on and I tightened. The light came back on I replaced the gas cap with a locking cap. My wife bought a code reader and I finally got around to checking the codes last week. They are P0449 and P0455 both emissions systems codes. After researching I was looking for the Evap Emiss Vent Valve Solenoid to see if it was easily replaced. I've seen forums discussion that say if done by owner it's less than an hour and $100. Didn't want to give money to dealer I didn't need to if I could help it. As I was looking I discovered the weep hole had been welded shut on the muffler. Besides condensation buildup rusting out the muffler what other problems would be caused because somebody welded the weep hole closed? Thank you for any advice and info.

 

blocking the hole will most likely lead to premature failure of the muffler...

 

Premature muffler failure is a concern. I was wondering what other problems might occur and if the latest codes might be associated? I know that there are 3 systems on engines. Electrical, fuel and emmisions control. With all the sensors now and knowing that these things work together, I knew there has to be consequences. Now if only I could conclude why the dealer decided to weld the hole after telling me its purpose and writing on work order receipt the following: {Customer states can look underneath vehicle and see a hole rusted through the muffler. Customer advised hole in muffler is weep hole. (Hole is designed for water to drain)} Knowing that and passing on that info to me and welding it closed just makes me grit my teeth. Thank you for the input. We'll be taking it elsewhere tomorrow morning after a little detour to the dealer to thank them.

 

No codes will be caused by the weep hole being plugged...If you drive long enough to heat up the entire exhaust system the water will evaporate and no problems, its short trips that cause the build up of moisture, the continual build up with short trips, is what will cause the rust out eventually....

 

First get the dealer to remove the weld and ask why they did it in the first place. Since the exhaust is st-st, probably won't rust out any time soon but still why risk it.

There are some good posts on the evap. solenoid replacement elsewhere in the forum. Use the search function to locate.