FInally got around to getting this done today. Was able to get to the plug from the top. Pulled the blue lock pin out and unplugged the connector without breaking the mount. THen I got under and too out the sensor. SHocked it broke loose from the pipe as easy as it did. PUt some antizeeze on the threads and installed the new sensor. Lowered back down and plugged back in. Not going to reset the light, want to see if it clears itself in the next few days. Then I'll have it read and clear any stored codes.

Thanks for the tip, worked great.

 

Well, ended up clearing the code last Thursday. Drove it around locally on Friday and no code. Saturday had to take a trip to Augusta and just as soon as I got off the interstate there, boom, cel again. Read the code at my brothers house and again, P0420. Was planning to go ahead and install the upstream O2 yesterday, but ran out of time. So that will be on tap for this weekend. But I'm having a feeling it's going to be the cat. So I'm still looking for one. The manual ones are hard to find. Still wondering if I could installed an auto one and just plug the bung for the upstream O2 the auto's have for the upstream O2.

 

In looking for the part by part number I ran across this on one site:

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Part information
Three way catalytic (with exhaust manifold pipe) (2005-2006 must order 25509274 plug for 02 sensor) (3.685)

Group: 03.685
Release dates: 2005-2007
Dimensions: 7.80 in × 40.30 in × 9.80 in.
Package weight: 10.91 pounds.

Now, this seems to tell me for a manual, I just need to plug that unneeded O2 bung. Does that seem correct since my O2 is in the manifold and not the downpipe?

 

sounds right , let me know if you want a newer manifold without the O2 sensor mount, then you could use the pipe mounted bung.

 

I'm finding several for 05-07 model GM's with this same basic cat. Some list 1 bung for the downstream 02 and some list 2. All have the same basic shape/bends. And all say they fit the 06 HHR. I'm narrowing one down to a stainless model with the single bung. Will be less than 1/2 what GMpartsdirect wants. More like 1/3. And no core charge. Finding Walker ones mostly.

 

I took these this afternoon of my downward view of my cat. As you can see, no upstream O2 in the pipe.






Now why wouldn't one of these this cat assemble work?

This one comes with the plug for the upper bung.
http://www.ebay.com/itm/290909590238...ht_2762wt_1220
http://www.ebay.com/itm/251199219595...#ht_977wt_1161

This one doesn't have the upstream bung.
http://www.ebay.com/itm/200750690214...ht_2221wt_1399

There are others, just picked these 3 from some I'm watching and they include gaslets and some hardware. Which I want also.

 

No one? Guess I'm just going to have to roll the dice....lol

 

(bump) IDK ?

 

I order a new downpipe assembly on Tuesday, supposed to be here on Monday. I'll try and get it in on Friday. Just hope I can do this on ramps. Don't have access to a lift. Ordered one with a single downstream bung and gastket set.

ANyone have the torque specs for the bolts?