I pulled these off my truck today, after performing the tests twice in the KOER mode. In the KOEO, the truck passed.

Code 172 in the Actron manual:

"Heated Exhaust Gas Oxygen (HEGO) sensor - voltage signal indicates "lean" (Bank #1)"

In Haynes:

"System indicates lean bank #1"

 

Probably you "fried" your HEGO sensor when you overheated the exhaust system. Replace it. Then reset the ECM - disconnect the battery for 15 to 20 minutes - and then retest.

Not living in NC, I can't help out on the passing inspection question.

 

It could well be a fried O2 sensor from your overheating exhaust situation . Found this link for other items to check that could trigger a lean condition first. The other code 538 seems to indicate improper throttle movement during test so wouldn't worry about it.

For continuously lean O2 sensor readings:

1. Check sensor output(oxygen sensor) wire for possible grounding. A ground will cause a false lean signal.

2. Check the MAP sensor for proper vacuum to voltage output. A high vacuum signal will cause a lean ecu reaction. (Don't forget to check manifold vacuum first!)

3. Clogged injectors can cause a false lean condition. A cleaning may solve the problem.

4. Water contamination will cause a lean condition.

5. Low fuel pressure will cause lean conditions at any rpm or load range. Be sure to check pressure at all driving modes.

6. Exhaust leaks, especially near the sensor can pull in air and cause a false lean reading.

7. Check for proper air injection system operation. The air pump should not direct air to the exhaust ports during closed loop operation. (ignore if no vac pump on engine)

I would add check all your vac lines for leaks.

 

The 538 code is probably due to your not punching the accelerator far enough during the Dynamic Response Test. It needs to briefly go all the way to the floor, WOT, so the TPS full range can be sensed & measured.
This is a faulty operator performed test, code & won't cause an IM inspection problem.

The 172 code Will likely cause an IM inspection problem & can be caused by a wide number of things as has been said.

If you know the O2 sensor has over 100k miles on it, it's likely time for replacement.

Seeing as how you say in a previous thread that you have a problem with the gas tank fuel inlet hose, be sure to add that to your suspect list, as the vapor recovery system applies a slight negative pressure to the gas tank to capture fumes to be burned in the engine, so if you have an air leak at the fuel inlet hose, it could cause a lean condition.

So can leaks in vacuum lines, brake booster diaphragm, intake manafold gaskets, dirty MAF sensor, dirty fuel injectors, low fuel pressure from dirty/clogged fuel filter, weak fuel pump, the list goes on & on, so we need some more clues to make more focused guesses.

You need to measure the O2 sensors voltage switching range & speed, to know if it's faulty, or just doing it's thing & sensing a real world lean condition. Will your Actron tool measure live PID feeds, or is it just a code reader???? If it'll read PID's, set it up to have a look at the O2 sensors PID output & see if you can see any voltage change.
You can also do this by back probing the O2 sensors electrical connector with your voltmeter, but it's a pia to do.

The 172 code will likely cause an IM inspection problem, so it needs to be put right beforehand.

More thoughts for consideration, let us know how it goes.

 

The first course of action for me is to probably change the sensor, which I believe I saw when changing the clutch and the cat. converter. Is it the oxygen sensor that plugs into the exhaust manifold right before the cat. converter? It looks to me like this thing is rusted pretty bad (its the original as pretty much the whole truck is, other than repairs I've made listed below). Maybe a few shots of PB Blaster?

The second course of action, even if changing the sensor does or doesn't solve the code problem is to fix that filler.

Another things I could do, which is easy, is clean the MAF, which has never been done. I can use break cleaner right, and just spray on the sensor part with the Aluminum chords, NOT the MAF box itself with the circuitry inside. I may even clean the IAC valve just because - it has never been cleaned either.

I'm in the middle of a very busy week so I doubt I'll get to any of this until Sunday afternoon after church.

Thanks for the advice everyone!

 

I would use electrical contact cleaner on the MAF. You want to clean only the very delicate filament of wire that protrudes from the sensor into air intake tube. If you remove the bed to work on your filler tube you will need your JB Blaster to soak the bolt threads(if accessible underneath) to make things easier as they are probably rusted in place. Might want to give them repeated sprays in advance of the day you do work to give it time to work in the threads. Also think you will need a torx head socket to remove them.I read that it is size T55 torx . Am sure someone here can clarify that.

http://www.autozone.com/autozone/acc...er=128435_0_0_

 

Well I'd first consider performing a thorough vacuum leak inspection, as they most often cause lean codes & it doesn't cost anything but a little time to do.

Test the O2 sensor before replacing it.

If everything underhood appears to be OEM, then begin by bringing the engine compartment up to date on all past & present due scheduled maintenance items like filters.

On your engine, the PCV valve & it's rubber connecting elbo are common sources of vacuum leaks. If the PCV valve is clogged up & stuck open, or worn & not sealing well, that'll constitute an unprogrammed for vacuum leak, that'll upset the system.
Of course you know about the inlet fuel hose leak, so as you said, that goes on the "do" list.
So what I'm saying is that you could have more than one vacuum leak source, so on your vintage vehicle, all rubber vacuum lines & their connections deserve to be high up on your suspect list.

Be sure to visit the "Tech Info" thread, located atop this forums thread listing page, for good "how too" info & make good use of the forums "Search" engine. Lots of detail on how to do the things your about to attempt.

Yes the "up stream" O2 sensor is in the exhaust down pipe, ahead of the cat converter.
If it's rusted up really bad & it laughs at the PB Blaster, or Liquid Wrench, maybe you'll want to use a good quality industrial strength rust buster, like Kroil, which can be ordered on line from Kano Labs, or most industrial supply or machine tool houses stock it. Warm the area around the sensors threads to help your product do it's thing & let it soak over night if need be, then use a special slotted socket for clearance relief of the O2 sensors wires, to remove & install.
Most autoparts stores have a nice O2 sensor removal socket kit in their "Loan-A-Tool" program, for a refundable deposit, that often makes removal & installation easier.
Use a good quality high temp nickle anti-sieze compound, like Permatex, on the O2 sensors threads, so it'll be easy to remove next time.

If you elect to pull & clean the MAF sensor, be sure to use a plastic safe, non residual cleaner, like CRC MAF sensor spray cleaner, be sure it's cool, don't touch it's wire grid & keep it squeeky clean upon installation. You can use the MAF cleaner to tidy up the IAC too.

More thoughts for consideration.
Keep us posted on how your trouble shoot goes.

 

Does the county you live in do emissions testing? Or does it do safety only on 95 and older like Jonston county does. If it does emmisions testing the amount of money you have spent on it should qualify you for an emissions waiver. So it wont have to pass state emissions testing.

 

What is an IM Inspection Problem?

 

https://www3.epa.gov/otaq/im.htm Failure of any of the vehicle safety, or emissions control systems that cause the vehicle to fail it's testing is a problem, unless we don't mind walking, or using public transportation.

EDIT: BTW, Welcome to FTE.