Can I change the upstream o2 sensor without replacing the converter gasket?

Hello DAVENOOB,

Unfortunately, you cannot re-use the gasket. The area needs to be cleaned well and all old gasket material removed.

Also, when you start it after replacement let it warm up while idling. The gasket will seat itself once it gets hot. If you rev the engine or snap the throttle before it has warmed up it can damage the gasket and cause it to leak.

Hope this helps.

Thank you,
Brendon

Thanks, perfect answer. Doing more research, I need to see what codes throw so I know which one I need to change. Besides that sensor, is there any other that needs gaskets to be purchased. Also, is that the only gasket needed if need to change all 4 o2 sensors thanks.

What is the name of the gasket for the upstream o2 sensor in front where mounts to engine block? Tried looking up but they didn't look right. Thanks again.

Hello DAVENOOB,

You're welcome.

The gasket is called an Exhaust Manifold Gasket.

The part number for both sides should be, 20893953.

Before replacing, let the engine warm up so the pipe is hot and use an Oxygen Sensor Socket. These don't normally come out easy so the socket will help and keep it from stripping.

Here is a link to a good socket. You should need a 22mm:
https://www.ebay.com/itm/394440429936?var=0&mkevt=1&mkcid=1&mkrid=711-53200-19255-0&campid=5338590836&toolid=10044&customid=86ad6777fd0216422080039222ca888b

I have included a picture from the GM catalog as well as removal/installation procedure for you. This procedure will be the same for all four.

From what I can see on my end at least, if you use the socket in the above link, you should not need to remove anything else to replace these, at least for the exhaust. Meaning you won't need the above-mentioned gaskets.

You can send me the code(s) and I can try to help you figure out what is going on if you would like. You shouldn't need all four at the same time.

If you don't have a code reader, places like Autozone and other parts stores will read the codes for free for you.

Hope this helps.

Thank you,
Brendon

Thank you so much! I'll get codes today from AutoZone and let you know. Thanks!

Hello DAVENOOB,

Okay. Sounds good and you're very welcome. Happy to help.

Thank you,
Brendon

So went to AutoZone and code p0449 evap vent solenoid valve control circuit. If this is bad, would it cause the car to feel like running thin? When accelerating when it's how at certain speeds it stutters like gasping for gas. When cold outside not bad but hotter it gets worse the symptoms. Thanks again

Would the evap vent solenoid value control circuit cause similar symptoms to upstream O2 sensor? The code for sensor didn't pop it just checks all the boxes for symptoms. Thanks

Hello DAVENOOB,

I apologize I didn't get back to you sooner.

Generally, a bad EVAP Vent Solenoid isn't likely to cause any noticeable symptoms, most of the time. Except for an illuminated check engine light.

However, it is possible, and I never rule anything out completely.

Let's start by gathering as much information as possible.

I know you said it seems like it is running thin? But gets better when cold and the hotter it gets the worse it gets.

Can you elaborate for me on these? What other issues are you experiencing?
What do you mean by running thin? Do you mean it seems like you have a loss of power?

When you remove your gas cap are you hearing an air whooshing like sound? Like pressure escaping?

When you fill it with gas, does the pump keep shutting off like it's full?

When are you noticing these performance issues?

If the vent solenoid is not venting, the fuel tank can pressurize. There is a solenoid on the intake called the EVAP Purge Solenoid. This is only open under certain conditions. If the fuel tank is pressurizing it could cause a rich condition when that solenoid opens.

As we know air expands and contracts depending on temperature. So, this could explain why the symptoms get better when it is colder, because there is less pressure in the tank.

Are there any certain conditions that the symptoms seem to arise, like for instance cruising on the highway or going uphill? How about driving slowly around town? How about passing or getting on the highway?

Any previous issues with the fuel system or work performed prior to this issue?

Because we don't have scan tool to look at the data the PCM is collecting, getting as much precise information from you will help a lot.

Taking it for a test drive to collect information would hurt either if you have the time.

While you are thinking about that I am going to get a couple test procedures prepared for you for that code that was found to try if you are willing.

We will need to see if the solenoid itself is faulty or something else is causing it.

Thank you,
Brendon

When I take the gas cap off no whoops. Uphill makes it worse and it happens around time to change gears. 45mph 60 mph. It shakes and stutters will down shift and raise rpms when struggling. All this started when I put the fuel injection cleaner in the fuel tank. Around town stop and go is bad. On highway is good if accelerating until hits a incline then down shifts and rpms jump.

Yes, it does constantly click off the gas pump. I have to hold the nozzle partially out, so it doesn't click off.

As far as temperatures I live outside Las Vegas so it can get very hot. 80° or lower no problems usually until start going uphill. The hotter the temperature outside the more it struggles. The steeper the hill the worse it is. I hope that helps.

Hello DAVENOOB,

Okay. Thank you so much for the great information. I appreciate it. I have another customer who has a similar issue.

I am trying to get some more information out of them right now to see what might match up with yours in case they are related.

So, we will see if we can get a little help there.

The vent solenoid usually we would use a scan tool and use it to turn the vent solenoid on and off and see if we can hear it clicking. That would tell us that not only the circuit and computer are working as they should but whether the valve is good or bad.

How comfortable are you with testing electrical components? Do you have a multimeter or a test light?

Thank you,
Brendon

Yes, I have no issue with testing. I believe I saw a video where you want me to disconnect the wire harness. So have an idea but please explain.

Hello DAVENOOB,

Okay, awesome. It is hard to tell in the picture you sent. Can you tell me what that is? Is that for 12v systems? Can you check for power with it?

I apologize, I just want to make sure the tests I send you match the equipment you are using.

Thank you,
Brendon

Just a power tester. Brand Allosun GK18b as you see works for outkes but I have a screwdriver type tester as well I believe just have to find.

Tells me if power circuit is complete for outlet so same idea 2 leads connected to a light.

Hello DAVENOOB,

Oh ok. Unfortunately, that is for 120-volt systems. We are working with 12 volts, so it isn't going to work for us. It probably only goes down to 50 volts.

Even if it did a test light won't tell us voltage just whether voltage is present or not.

Let's see if the solenoid is good or bad. It is usually mounted in the left rear quarter panel behind the back wheel. There was an update GM did that moved it so if it isn't there look by the filler neck or up closer by the body. I added some pics to help you identify it.

You are going to take a fused jumper wire from the battery positive all the way to the vent valve solenoid.

We are going to run straight power to this thing and see if it moves.

Remove the connector from the valve.

Make a ground with 14-gauge stranded wire and attach to frame or known good ground. Then using an alligator clip and attach the wire to one of the prongs on the solenoid.

Then take another alligator clip and attach it to the other prong on the solenoid and then quickly touch the fused jumper to the alligator clip. This will make a small arc so be careful, but this arc can damage the terminal. That is why we are going to attach the alligator clip and touch the wire to that.

Once this is done you should hear a soft thump kind of sound. This is the solenoid moving. That means it at least moves. So that means our issue is likely something else in the system and further testing is required.

Insulated alligator clips are best but uninsulated ones can be used with caution. They must never touch. Using electrical tape around the alligator clip and making a cut so it can still open and close will work to insulate the clip.

If it is easy enough you can remove the vent valve from the vehicle and bring it up to the engine compartment and test it the same way just instead use battery negative as ground. But then if it works you removed a working part for no reason. So, I will leave that up to you.

10–15-amp fuse is good enough for the jumper wire.

Let me know if you have any questions.

If we can find out if this thing is the issue or not, then we can proceed from there.

If not, from here we will need a multimeter to check the computer side and see if there is a wiring issue.

Here is a link to one I own. It is inexpensive and accurate:
https://www.homedepot.com/p/Klein-Tools-600-Volt-Digital-Multi-Meter-TRMS-Auto-Ranging-Temp-MM420/320822810

Thank you,
Brendon

So, I need a voltage meter. Would this work or do I need a multimeter for automotive? Does it make a difference?
So, I'm done for tonight after work going to pick up whatever you suggest just can't do $60.00 right now. Talk to you tomorrow. Do you communicate on weekends? Make sure to tell me how to donate as well please you have been more helpful than 5 days of internet scouring and dealing with automotive stores who aren't smart, lol. thanks

Hello DAVENOOB,

Okay, sounds good and thank you very much I appreciate that. Happy to help! Yup, I am here 7 days a week. I run my own business so sometimes it might take me a little bit to respond though.

Also thank you very much for any donation, we really appreciate it!
Here is the link for you:
https://www.gofundme.com/f/help-us-help-others-get-back-on-the-road?utm_campaign=p_cf+share-flow-1&utm_medium=copy_link&utm_source=customer

Thank you so much!

A multimeter is best, that way we can check voltage and resistance.

The one in the picture looks like it should be fine.

Main things you will want to look for in a meter in my opinion is that it is Auto-Ranging but should still have a button that says "Range", so you can change it if you need to, backlit screen, and an audible continuity tester.

None of these are necessary but nice to have.

Looks like the one in the picture has an audible continuity tester so I would say that one would be good enough. I have never used that brand though. It is manual ranging, which is fine, you just have to make sure it is in the right setting.

This video will show how to use a manual ranging meter and how to set it:

https://youtu.be/xoH3COn57JA?si=_eQTrLhDP9Q63dqp

Fast forward to around 4 minutes.

If you pick one up at the store, I recommend grabbing one from the back of the shelf because people look at them, then drop them accidentally, look around and put it back. Then you get it home and go to use it and it is reading all over the place.

Grabbing one from the store is better anyways so you can return it quickly if there is an issue.

Hope this helps. I will get some tests together for you and send them over as well.

Thank you,
Brendon

Awesome man, thanks. I'll make sure I can do what you recommend. Thanks again for the videos.
If an o2 sensor code didn't show, is it possible that o2 sensor could be faulty? Sorry, I'm no mechanic but o2 or fuel pump/filter but more towards o2 sensors. New cars suck kind of my old 1977 was great so easy not a bunch of electrical.

So just accelerated on to the highway and if giving gas to accelerate and no issues speeding up to 95mph even uphill. If at a set speed or have to increases and decrease on highway more so up hill is the worst.

Hello DAVENOOB,

You're welcome. Honestly the newer they are the worse they get. I will never buy a new car again. I would rather it be simple than all this electronic stuff. It can be very frustrating. I rewired an entire 72 Nova in 2 weeks, cars these days you pull apart one harness and there is over 30 circuits in it. It is not ideal.

It seems like it is having some kind of issue affecting the fuel/air ratio causing drivability issues. However, without a scan tool to look at what the computer is recording, I think the best thing to do is go with the one code we have and see what is going on there.

It is possible to have an issue with something like the O2 Sensor and not have a code, if the conditions for the code to be set hasn't been met. Things like the fault needs to happen for a certain amount of time, with the engine at or above a certain temperature, while it is in drive or things along those lines. All codes have different conditions for setting the DTC or Diagnostic Trouble Code.

This doesn't mean there isn't a problem in that area, it means the computer hasn't caught it yet.

Also, some codes can be current, others can be pending, and others can be history codes. It depends on the scan tool or code reader whether you get any codes but current or not.

However, something like an O2 sensor is Emissions related, so these codes usually show up very quickly if there is a problem and don't have a lot of parameters, they need to meet for the PCM to set the code.

It is possible for the EVAP system to cause drivability issues, so I think figuring out what is going on with that code and getting it fixed, should be our first priority.

Once that is out of the way, we can see how it is running and go from there.

Could be worse we could have ten codes and have to sift through all of those, lol.

My thought is if the valve is closed constantly, it would cause you to not be able to just fill it with gas without the pump shutting off. My 2003 Blazer did this to me. Loved that truck. Took me like 15 minutes to fill the tank. Had a vent valve code, switched out the valve and finally after years of dealing with it, problem was gone. After working on other cars all day, the last thing, I wanted to do is work on my own, that's the only reason I dealt with it for so long.

But since a wiring issue is a possibility and you will have a multimeter, we can test the wiring and the valve safely. We will skip running a jumper wire for now. The valves tend to get dirt in them, so GM redesigned them because they were getting water in them.

So, I will get some tests together for you and we will just make sure it is the valve, so we don't replace it prematurely. If it isn't we will check the signals coming in.

Thank you,
Brendon

Hello DAVENOOB,

What was the vehicle temperature? Was it warmed up fully? Also, what is the temperature outside?

Thank you,
Brendon

Hello DAVENOOB,

Also, when under heavy acceleration, like getting on the highway, the purge solenoid under the hood will not be open. Usually, it is open when the engine is up to temp and cruising at part throttle, so I think we are in the right area.

Here is the first test:

So, on the connector for the vent valve there should be a WHITE wire and a RED wire with a WHITE stripe or tracer.

WHITE-Solenoid Control- This is a ground wire that is switched in the PCM using something called a driver. A driver is simply an internal switch in the PCM. When the valve needs to be energized, the PCM simply just completes the ground also called the control.

RED/WHITE Stripe-Battery Positive-Should have 12 volts with key on engine off.

Place meter on second up from lowest setting on DC voltage. Should say 30 or 40. The symbol for DC is a straight line above a dashed or dotted line.

So, we will do this first. let's make sure we are getting battery voltage at the valve:

1) Unplug the connector at the vent valve:
-Turn ignition key on with engine off
-Take BLACK lead and touch to ground, the frame is fine. You might have to scrape it to get a good connection.
-Then touch RED lead to the terminal the RED wire with the WHITE stripe on it.

You shou see 12 volts or close to it.

Note results.

Next:

1) Put meter on lowest setting for DC Voltage. Putting it on the lowest setting will give us milli-volts.

2)With the connector still unplugged:
-Touch the RED lead to the terminal for the WHITE wire.
-Then take BLACK lead and touch the frame again for ground.

You should see 0.1 volts which is one millivolt and is considered a good ground.

The PCM will connect this to close the valve and let the tank build pressure/vacuum to test the system.

Note results.

Let me know what you find, and we can take it from there.

Also let me know if I can clarify anything, sometimes I am not the best at explaining things.

Thank you,
Brendon

So, the car was to normal temperature outside about 90° live outside of Las Vegas so can get very hot. It should be at least 100° on the way home so I will be able to do more driving tests if you'd like. We accelerated constant going up hill and got to 90mph no shake. Usually if not accelerating going up any incline will start gasping or chugging shaking. Since it struggles it will down shift and rpms jump to 4-5k unless let off gas then will up shift again. The car at normal temp and 70° outside hardly notice over 85° it's bad 95°+ really bad and it gets to 115° so you can imagine.

So just make sure the meter have an auto switch. Okay, will check your other specs when purchasing.

Hello DAVENOOB,

It doesn't need to be auto-ranging. The auto-ranging ones will have a switch that says "Range" so you can manually adjust it.

I think the one you sent me should be good enough.

The auto-ranging is a nice feature, so you don't have to keep switching it yourself, but it is not necessary. The cheaper ones normally don't have that feature.

You can always upgrade down the road.

You can keep driving it around if you would like. The more data the better. It sounds like the torque converter is stuck in lock-up. However, if the engine isn't running right, it will cause transmission issues.

The best thing to do in my opinion is to get the multimeter and let's see if we can get this vent valve issue fixed. Then we can see how it runs and go from there.

If it were my vehicle that is where I would start.

Thank you,
Brendon

This is what I got.

Hello DAVENOOB,

Looks good from what I can see, let's hope it is decent. First thing you are going to want to do is put black lead into "COM" and the red lead in the middle hole.

Then set the meter on ohms, looks like a horseshoe kind of and try setting it at the "200" scale.

Now touch the 2 leads together and see if there is a reading. It should be zero or close to it.

Let me know if it isn't or you get OL or an I.

If it checks out good. Then set to DCV on 20. Now test the battery and verify you have 12 volts or close to it.

If so, then you can start testing for power at the connector for the vent valve.

Also visually inspect the wiring and the connector for any damage or corrosion.

Here is a good article about what to look for when checking wiring.
https://www.2carpros.com/articles/how-to-check-wiring

I have already added the tests for you but let me know if you can't find them and I will resend them.

Let me know if you need any help.

Thank you,
Brendon

Awesome thanks I'm starting to work on the car after morning coffee will keep updated got good to work with.

Set on ohms at 200 and it read 00.7, is that about right?

Battery hit 12.43 so I believe this is correct.

Hello DAVENOOB,

Ohms seems high. Leads could have some resistance in them. Did you measure 12.43 at the battery or at the connector for the vent valve?

Thank you,
Brendon

Hello DAVENOOB,

Sorry just read it again. Sounds like it was the battery. Now unplug the connector on the vent valve and see if it has power with the key on engine off on the red wire with white tracer/stripe.

You should have close to the same that the battery had, 12 volts.

Thank you,
Brendon

Do my dcv is 250 200 20 2000m 200m where would I go? Sorry electrical is Greek to me. It will be set for DC voltage measurements right so top left side. Should I go with 20 or the 2000m?

Hello DAVENOOB,

So right now, you are on 5 amps. Move the switch around the opposite way and put on 20 DCV. The dot is like your arrow.

That should be max 20 volts.

It's ok. I am here to help. This is why i recommend the auto-ranging instead of the manual ranging. But it is alright, there will just be a little learning curve. No biggie. We will get it.

Thank you,
Brendon

I know I knew the switch wasn't in the right spot I should have put to where I thought it was supposed to be sorry. So videos so lift and pull harness how do I get this use a screwdriver to slide the red lever up?

Hello DAVENOOB,

No problem. Don't worry about it. When you say red lever do you mean for the connector?

Like this? (See image)

If you can, take a picture for me.

Thank you,
Brendon

No thumb release and red tab won't go in or out.

Hello DAVENOOB,

Try some WD40 or PB Blaster if you have it. Brake clean will work too. Dirt is probably lodged in the keeping you from pulling it out. It might only come out a little and then from what I can see you can push on this tab to see image.

A pic or small flat head screwdriver will help as well.

Because of its location, it collects a lot of dirt so soaking it in some kind of oil will help a lot.

What do you have on hand for oils and cleaners?

If nothing, I know this sounds odd, but a couple drops of olive oil might help if you have nothing else. Put a drop at a time on your finger and let it soak into the connector.

Worst case sometimes the red lock will come out in pieces unfortunately. Not a big deal though the lock isn't necessary.

Thank you,
Brendon