Exhaust Manifold Repair Triggers P0154 Code

[Alibireason]

Two days ago I had my driver's side exhaust manifold replaced on my 1998 Pathfinder (CA emissions). Shop quoted me $625. Same shop had done minor work before and I liked how they did business. Upon arrival to pick up he shows me old manifold, It was broke in two, and he told me he had to charge full price because of just how hard it was to remove ($670 with tax). No problem, I appreciate the hard work. Fire it up and it sounds great, much quieter and stronger feeling. Its end of day, mechanic leaves as I'm warming up car. Next thing, in park, rpm jumps up to almost 2000 and starts whining, then drops back. Then I check and Engine Light is on. Plug in my scanner, it reads P0154. I clear it and drive home and code comes back (5 mile drive). Once home I open the hood, smells like burning rubber. I notice tube coming down from EGR is side by side touching the rubber tube coming from power steering reservoir. WTF! I think. Then I notice he didn't put the heat shield on. He just didn't do it (probably from the difficulty he mentioned earlier but who knows).

Next morning I check 02 sensor, its tight, and my common sense told me to move the power steering tube away from the EGR tube. I clear the CEL again and drive for about 30 miles. The RPMs didn't spike at all and the CEL hasn't come back.

I'm curious to get opinions from others about these thoughts:

No heat shield? it it necessary? or were they lazy?
HOT! EGR tube literally touching power steering tube (it did start melting)
Not informing me of CEL.

Do you thing my CEL will come back? Does this story sound like a "normal" exhaust manifold replacement?

[VStar650CL]

Too much or too little airflow around front O2 sensors can definitely cause some odd behaviors. For instance, a design error on the '16~'17 Altimas had us cutting holes in the front underpan and grille shutter to get rid of P014C/P014D/P015A/P015B DTC's, which are the wideband analogs of some O2 DTC's:
https://static.nhtsa.gov/odi/tsbs/2016/ ... 3-9999.pdf

So yes, I think it's possible the missing heat shield could be causing issues with your front O2's. You shouldn't be without a heat shield anyway. It isn't there just to protect the car from the cat, it also serves to protect the cat from the car. To learn why that's important, read the final post in this thread:
post6820520.html

[Alibireason]

Thank you for replying. I am going to take the car back on Monday. But I have a feeling he will tell me he doesn't have the heat shield or something. It boggles me that he didn't install in onto the exhaust manifold in the first place. I checked a couple forums of people saying they just leave theirs off, but I'd rather not.

VStar you mentioned the heat shield in relation to the catalytic converters but does the same logic apply to heat shields on exhaust manifolds? I am going back to ask that he install the heat shield. I have the feeling he won't have it though. Don't exhaust manifolds always come purchased with heat shields?

[VStar650CL]

The manifold and cat are integral on the Altie in that other post, but on any modern vehicle they both get very hot. Rule is, if the OE put a shield there, then it's there for a reason. Part of the engineering reason, unknown to us, can be to induct or deflect hot air to help the lambdas and O2's maintain temperature. So for any number of good reasons, f#cking with it can cause problems, some obvious and some not.

[Alibireason]

UPDATE!
I went to the shop yesterday. I asked if he knew he gave me the car back with a CEL. He did not. I asked about the heat shield. He had no idea if the new manifold came with one, or why his tech did not install it. He mentioned space clearance as a reason to which I replied "if the tech could get it out, shouldn't he been able to put it back on? I mentioned the possible importance of needing the OEM heatshield on there and he replied with "no heat shield does help exhaust manifold breathe better." He was defending idea of no heat shield.
He had nothing to say regarding the rubber tube being positioned touching the EGR tube.
He did say he would work on finding me a heat shield (installed free of charge) and call me by Thursday.

Is this experiencer I'm having considered "normal?"
I'd love to hear some opinions!

[VStar650CL]

That's like asking, "Is human nature normal?"

Nobody likes to admit that they screwed up.