The "massive exhaust leak " being the flex pipe? That will cause the #1 O2 sensor to think it is running too lean and try to adjust, sometimes causing a too rich reading. So, don't replace the sensor until the code clears itself.

OK, putting my turban on now; P0171.

Cracked flex pipe is one of the top 5 most discussed topics here.

 

Thanks for all the replies.

The car's in the shop right now, getting a new exhaust put on. The flex pipe has been bad for a while and according to the shop that fixed it easy last time, he said it was too far gone and had to put on a new system with a new cat. Not sure how that is possible but he sure will make more money.

Anyhow, the o2 sensor was intermittent before the flex leak.

What baffles me is why putting in more gasoline allowed me to start the car.

He said I was misfiring on one cylinder and compression was low so he's cleaning the valve ports as well and putting in new plugs.

I'll let you know how it all goes.

 

This is the value of getting codes read! Now you are dribbling symptoms in. That would indicate a charcoal canister purge or vent problem.

Seemingly unrelated codes can mean something, don't leave them out.

I think you mean the crack in the flex pipe got bigger not that the code was intermittent.

 

Thanks for your reply Don.

There was only every one code being given: that is the one for one of the o2 sensors. It would come and go. The last time I had a check engine light, it was for that code, and it was roughly Spring of 2015. It went away, inspection passed, and that was that.

No check engine or new codes since then which is why I didn't think of mentioning it in the original post.

Fast forward to December 2015 - developed a crack in flex pipe. Still no new codes given.

Fast forward to March 2016, symptoms described in original post.

 

Fast Reverse If we knew the code we could have told you to check the flex pipe.

Unless it occurred more than you describe adding gas has nothing to do with it, the time it took did.

" he said it was too far gone and had to put on a new system with a new cat"
He doesn't know how to weld a new repair flange/flex onto the pipe? If he had done that with a repair part first it would not have failed again, they are different designs. Or, do you mean all of the pipes are rusted out?

If this is the second time you need to look at motor/transmission mounts, they have probably been bad since the first flex joint failed.

I got more, but I'm tired.

 

Thanks for the info, everyone. I came back to advise so I wouldn't be another one of those OPs who drops a question then disappears.

OK so here's the update on what happened.

Dropped car off at the shop - just a few blocks away from where I stalled and close to home too.
Mechanic advised that (in addition to the exhaust leak) I was misfiring and compression was low. This is as much info as I got from him, and I didn't know any further specifics to ask. There was no Check Engine Light on at the time. I have since learned that there could have been codes present at the time, even if no CEL, however I did not know this at the time and didn't know to ask, and I am fairly sure they wouldn't have checked.

So here's what they did: replaced the exhaust, including the cats. I know, this had nothing to with the engine stalling, or fuel delivery, etc, but it had to get done anyway and the stink in the cabin was getting to me. :)

To remedy the misfires and compression, he replaced the plugs and airfilter. Bummer, I could have done that myself but c'est la vie.
And then he ran a BG intake cleaner, the one with the canister and "iv" drip into the air intake. God only knows if any of this works worth a damn but I went for it.
The car did seem to be running better after that.

Better, that is, but not well at all.
After driving it around for a couple of days, it still felt like it was going to stall out on me, whenever I was driving it in town, around 30-35, and slowed to a stop or to take a turn onto a side street - unless I put the automatic into neutral, and then back into drive.
That's no way to live.
So I've been reading up as much as I could on it.
(btw, I have the 2008, LT, 2.4 engine)

Wouldn't you know it, it starts with the CEL a couple of nights ago. So I grab the code reader which lives permanently in my wife's 2003 Hyundai. (It's a 13 year Hyundai, so it's pretty much required by law.)
I had P0014 and P0171.
Ok, so I started with P0014 - the exhaust side camshaft position actuator (not sensor).
I read up on why the actuator might go bad, and learned that it actually uses oil pressure to work.
I went to check and wouldn't you know it, the oil level in the engine was low as hell. I put in a couple of quarts and gave it a road test.
No more stall threats when pulling out of my driveway, or slowing down for a stop sign or a turn. No more hard shifts either.

I cleared both codes and am running pretty well at the moment. I'll give it a few days and see what's what.

I can keep updating if anyone finds it helpful. People tend to search this site as much as post, I would guess.

 

Yes, certainly keep updating! How did it escape from the mechanic with the oil level so low? Or is it consuming or leaking oil that badly? Better keep an eye on it.

 

"including the cats. I know, this had nothing to with the engine stalling, or fuel delivery". You know that, huh? Yes it does.

If there was more than 2 misfires in a drive cycle there would be a CEL.

What did they say killed the cat? If they didn't fix that, the new cat will die soon.

I don't trust your mechanic if he didn't check the oil. But then, maybe you are burning oil and that's what killed the cat.

Why did you feel compelled to clear the codes? They will clear themselves when the condition is fixed. Now, you may drive for a couple of weeks before all the OBDii test are run and suddenly , CEL!

 

Dunno Don. I'm not pretending to be an expert. I am checking forums for help from people who are or are pretending to be, and now my IRL mechanic appears to suck.
I thought the exhaust was a separate issue. Remember: this all started because the car seemed to run out of gas and have a broken fuel gauge. I added 2 gallons of gas and the car was seemingly fine, leading some on here to advise that the fuel pump was going.

What killed the cat seemed to be salt and rust. Or at least, all the metal surrounding the cat.

My trust in my mechanic has been neutralized as well. Maybe it burns oil but there's no smoke, and no leaks. It had been overdue for an oil change and I am obviously a poor vehicle maintainer. The DIC started saying "Change Oil Soon" a few weeks ago so bad on me.

I felt compelled to clear the codes because I didn't know how quickly they would clear and I wanted to see if adding the oil to correct the cam position issue was indeed taken care of.

Thanks folks.

 

Before I got the HHR, I was driving the neon. I knew it burned oil, not terribly, but it did consume some. Yet every smog check was clean, I mean really clean, and it didn't smoke either. When I asked the mechanic about it, he said that the oil was going into the cat, and I would have to replace it at some point.

So yes, just because it doesn't smoke, burning oil is bad. MmKay...