Rep Power: 0

A real newbi move on my part... I wanted to remove the heat shield to remove the air/fuel sensor to test it for a momentary cel and code p0132. Code disappeared but I cleaned the wiring and connector anyway. Removed the top 2 bolts(which are also exhaust manifold bolts?) and started on the bottom bolt, felt like it was turning but I really rounded it, 12 point socket...dummy me. It's really frozen and very little room between it and fan. My extractor set sizes are too big or too small, can't hammer the smaller on, no room. Feeding it Blaster to no avail.

Favorite method or tool for this bolt in this tight location?

 
Rep Power: 222

Grind it off

 
Rep Power: 244

Vice grips and if they are not enough cut it off.

 
Rep Power: 0

I'm on repair hold till the holiday rush is done but I was looking at the exploded view on my Alldata. Does the bottom heatshield bolt only thread into a welded bracket on the exhaust manifold? Can I access the bolt (and sensor) from underneath or is the cross member in the way? Thanks, I'm just getting to know this car, these are probably simple questions but I didn't find previous threads with this info. There are a lot of lx/dx 3 way cat converter/o2 sensor youtube videos, not so many of 03-05 ex vids.
I have to replace the radiator fan soon so there will be better access if I also remove the ac condenser fan while it's all apart.
I could cut off the bolt head for the sensor access but still want to correct the bolt issue.

 
Rep Power: 512

It's been a while since I took a look at an OEM D17A2 exhaust manifold, but I'm 99% sure it's a welded bracket onto the mani itself. Both o2 sensors should be on the downpipe (one just after the mani-downpipe flange, one post-cat). You can access the primary O2 sensor from top or bottom. If you can, remove the manifold entirely then work on that bolt. I think you should be able to remove it from the car without separating the heat shield from the mani. Getting the manifold out of the way will make your life easier (but depending on rust levels, might be a pain to remove)

 
Rep Power: 0

update:
I have not gone any further with my rounded heat shield bolt but I did access and change the o2s1 from below. No problems with that and I did pass Ct emissions.

 
Rep Power: 0

Update:
With the 2 upper bolts removed, I am rotating the shield back and forth and adding blaster to the bolt/flange. It is getting looser, hoping the rust is giving way. . Determined to remove the bolt intact. If I grind the head off, I'll still have no room to use an extractor/bit. Cannot get a bite on the rounded head with visegrips as the shield bolt hole is resessed, just to fit a socket. May have to remove ac condenser fan etc to get access.
Getting this done now so that when I really need that shield off, this issue will already be solved.