We got another Buick here folks, it's Dean Cafe Uh, we'll look and see what here it is here in a second lady says that the engine light is on and it is I saw it when I drove it in and she also has a complaint of the tire pressure sensor light on which it was. So let's turn the key on here. This a service tire monitor system so I assume it just has a sensor going bad so let's see what we have in it for codes for the engine light. So we got a PR Now it's a little easier to see in that screen so it looks like we got two codes in the engine couple in the HVAC module and remote control door lock receiver so that would be your uh TPMS here on the shevy uh engine wise, what do we have here? We got a P 119 engine coolant temp sensor circuit intermittent so that's interesting and then a small evap leak which is never a big surprise on General Motors and then our TPMS right front tire pressure sensor and right front tire pressure sensor.

So assuming they're in the correct position, never never diagnose a uh GM based off that code alone. So uh I guess the one thing we need to look at is that uh P19 engine cooling temp sensor circuit intermittent so that's kind of interesting I wonder if there's any Freeze Frame data on that? There going to be a bit of a glare, but we're going to go over here to this little snowflake. Oops. try this again and see what it was doing at the time of failure and see.

see what it recorded. Yeah, see, at the time the time it recorded, it was 185. F Let's see if there's any other yeah. Intake Air Temp was 75 Already been running for 4 minutes, so that's plausible.

Um, so I guess it didn't capture it at the at the moment there, so that's pretty interesting. Um, now I just started the car up to drive it in so it shouldn't really be warmed up up. Uh, but I'm not going to make a classic rookie mistake. We're going to back right out of OEM data.

We're going to go. We're going to go into generic OBD2 So, and the reason we do that is, we don't want to get uh, snuffed by a substituted value. So when we look at OBD2 data, we're going to see raw data all the time. So we've just got the one code here.

it says let's see so this is only shown codes for the EVAP leak, current pending, and permanent. Oh H Let's let's watch it go through a warm-up cycle. Anyways, here, as we can see right now, it's sitting about 93. F Uh, underhood Intake Air Temp 2018.

Pretty toasty out today for October Um, so I'm going to take and start it up and then we're just kind of see if the coolant temp sensor glitches just a normal start up and then we'll do a, you know, visual inspection, maybe wiggle the connector things like that if that makes sense. So I'm going to watch this warm up if it does something funny I'll kick the camera back on. but in the meantime I'm going to look up, see where this coolant sensor lives. Uh, but I just kind of want to let it go on its own for it.

now before we touch anything 25. apparently it goov right down there by the oil dip stick. it's got that sleeve around it. boy this looks awful familiar.

like I've done one of these in the past I don't remember why that looks awful familiar to me there. we just saw it get dumb I wasn't even paying attention but it's was holding here about 170. Oh yep, there it goes. See all right.

So now you guys are seeing it. it was holding like say about 170 I look over and I was kind of coming down I was like oh it's weird, maybe thermostat just open but then I just like Boop dropped down to like 140. but now you guys can see it glitching so it must be right around that. Yeah, so it's going 138, 147, 174 back to 180.

So yeah, it gets about this temperature so that makes sense with our Freeze Frame data that we saw because the freeze frame was showing 185 and that's probably where we're about actual temperature and then that must be where it. uh, where it starts glitching. All right. So yeah, not a big deal.

I am kind of curious if it set a uh, pending code for that. Uh, code set criteria was like had to have a greater than 9 fluctuation. you know, imp plausible. but yeah, no, it didn't set a pending code for it.

but uh, clearly we see that it's an issue. Uh, some things to keep in mind. Uh, you know, prior to doing that, obviously make sure it's full of coolant. You know, the normal stuff.

Uh, I I Was just speaking with the customer a minute ago and she did, kind, uh, state that she's been noticing that the temperature gauge was fluctuating up and down erratically also so that also aligns with uh with that coach that she' just be driving along and she'd see the gauge drop down and then go up and then drop down and then kind of read right and then it would be a little while after that she'd get her engine light. So uh, at any rate, I did check the local part store does have one of them bad boys take and get this thing out of the way and I think the other thing we ought to do before we get two carried away. Let's find out which uh, which tire sensor has gone bad in this thing. Start right here on the left front.

trigger that one we'll go around I think it was the right front that was, uh, suspect according to the code and and as I told you guys, sometimes that doesn't always stand true because if somebody didn't program them when they rotated the tires, then where the car thinks the right front is, it isn't But in this case it looks like it probably is cuz this should have triggered by now. I'll let it go till it times out all right. We got the big fail on that one, so come back here with us. Double check all of them here.

Usually they trigger pretty quickly and then what we got left is the left rear Checker that one. Okay, so indeed this one is correct. The right front has failed I Keep these altel MX sensors in stock dual frequency. They cover everything we ever work on so we're going to pop out into programming.

We'll select right front. We'll go autocreate. It's going to look for the sensor here and uh, we'll identify that in a minute still in the box and then it will just write a unique ID to it. It says one Center detected hit.

Okay, it's going to write uh, you know, a unique ID to the sensor and then we'll just pop it in the wheel and then we'll just, um, you know, retrain the sensors once they're on the on the car. So let that finish. These Altel sensors have been great for us and they're relatively inexpensive too. You get them at Rad out.

Napa All the all the car places around here s them you get them on Amazon But um, and then this is the it 600 uh by all. so this tool is pretty handy so that's that. Let's get the wheel off. Um.

I've got a coolant temp sensor coming for it so we'll get after it so this could bring up the question just real quick. We'll address it. Um, how do we know it's the sensor? Well I I guess to be definitive, we don't. we can assume, but we can do a quick circuit check on it.

So right here I've I've gone and unplugged the coolant sensor. kind of a piss pot to get to. It was toasty too. I put on a glove.

Uh, so we're At-40 That's what we expect to see and then when we short it, it should go to around 300. I'll put it in a uh graph here because I can't hold it and do everything here all at once. We're just going to short it with a pair of pliers if we can reach across it which we can't let me get a couple T pins just going to lightly front probe it and touch the pins together. Yep, and it went up to 3.

302 is Max temp. So 302 that's totally shorted and then back to minus 40 open circuit. So that tells us that our wiring from here to the PCM is good. PCM can calculate probably just through a code there here.

dinging. You know? Granted, you could have a PCM that's failing and this and that. Um, the sensor is like you know, 20 bucks so and it only takes a minute to change so we're going to just swap that out. We'll let it go through a warm-up cycle and and that's that.

So kind of an easy one folks. So the other thing we we have to look at I Almost forgot. Um is the uh small evap leak. So we're going to go into active tests here.

We're going to go into the Uh vent valve and we're going to look at fuel tank pressure. Okay, so fuel tank pressure right now. Uh, we should be atmospheric pressure. So this one it's reading 1.43 We're going to close the vent and it's pretty warm out.

Today it's like 80. We should see an increase in pressure here and that's what we want to know is, you know how big is this leak? Uh, the gas tank should be warm enough that in a period of time here that should start to build pressure. it looks like it's building it pretty slow. I Would have thought it been a lot more volatile than that.

Um, I how much and it says a 10 gallons, just under half a tank can revent. Vales obviously working here, but we can see we're not building pressure very quickly here. We going to go back. We're going to revent it.

Yeah, hardly changes it all, you know? Okay, let's just have a look at the uh obvious this is a dirt road car. Guess we got to find the clicker for this thing. Mind I Just didn't click it hard enough. just see if our filler necks all rusty.

and it is. So the top of the filler neck here is is pretty dang. Rusty it's probably where our leak is at. Um, not going to hurt to clean it off anyways, but this is super common around here.

The top of the filler neet gets super. Rusty So for this next bit, I've gone ahead and I've removed the uh fuel tank from the car. Uh, you definitely would not want to do this with the fuel tank in the car. so take the fuel tank out, remove it all the precautions.

so there's that. I just use a Uh Brash cup there from the Harbor Freight You know. But again, don't do it with the gas tank in place. We're going to take a little bit of s Glide from Napa not a sponsor.

We just rub a little around that lip. kind of slow down the rust a little bit if we can. Is this the leak? I'm not sure. Was it a problem? Yeah.

I'm going to put that on there. get Mr Hanky again here. little shoo on the cap. Okay, we're going to go to not venting.

Okay, it's not vending, it is closed and then we'll see if it can start to, uh, accumulate pressure. uh and see how quickly this is. Just kind of a quick and dirty test. Uh, it doesn't always work.

Fuel has to be pretty volatile. Uh, we may end up just throwing a smoke machine on it here. Well, let's give it a minute or so. No real change there.

Let's just do one other thing here before we hook up the Uh. Evoca Smoka. Let's just start it up. I Want to make darkn sure the purge isn't stuck open.

These cars are pretty good about setting codes. If they are, we're going to start it and we don't want to see any pressure change here. We're going to go to Not venting. We're going to close the vent.

Oh, you see that it's putting it under a vacuum, but we shouldn't have any Purge running right now. we don't Purge is at zero and it's drawing the tank into a vacuum. So let's go to. let's go to Vending.

Let's open it up. Purge valve. Oh, purge valve. Just open here standby.

It's going to be noisy out there because the uh, coolant sensor is unplugged. I Got the engine off right now. We're going to go to Purge Valve I Think we just have a bad purge valve, which wouldn't surprise me. We're going to keep this.

We're going to keep it commanded at 0% and then we're going to look at tank pressure that should not change. Okay, so let's go ahead and start it and it automatically puts it into a vacuum. It starts drawing it even though our Purge is at zero. You can see um, you know from where it was it was A you know, 0.19 It's not leaking much, but it's leaking.

So let's pop back out of here. We'll go to vent valve test me, shut the car off and back on. I Just want to make sure there. So our purge valve is at 0% we're going to go to not Vending, We're going to close the back door.

We're at 0% We should have no vacuum in the tank and you can see it's immediately putting the tank into a vacuum even though the purge is at 0% So we have a bad purge valve so that's easy. So the reason I Check it like that: A it's easier and b sometimes you touch these suckers and they start working miraculously. So we're going to try to just squeeze the tabs here. unplug it.

So this is. this is the vapor line. Oops, that might have just made it start working. Usually whack them of the screwdriver that work in.

This is the vapor line that runs to the tank and then to make sure it's not stuck electrically, we just simply unplug it. But sometimes that's all it takes and then they'll start working again. So let me, uh, see if I got I got a vacuum gauge here? Here we go. Let me get it out of my twool box.

Don't use this baby too often. We'll hook it up and you guys should be able to see the vacuum on it providing it's still broken. like I say sometimes a little screwdriver whack will make them work again. stick that on there.

Going to go ahead and start up, the fans are going to be roaring again, but if this is still broken, it's completely unplugged so you know the PCM can't be commanding it and then we should see it build vacum. This is often overlooked when it comes to evap leaks, but if you don't understand how it runs at small leak test that get you every time you're done. for lawnmower, there we go. we have full engine vacuum.

All right. You guys can see that we got lawnmower man out there. o I don't have a screwdriver but I got this thing whack it a little bit still have vacuum. No this one's broke, broke, broke broke so he wide open wide open throttle on this one.

All right so that's easy set off I stuck a uh little test port inside this plug here. not going to click it all way I just want to be able to hold my finger over it. We're going to go back to the vent valve test and we should to be able to see the tank buil pressure. Now let me turn you guys down here.

I'm just going to hold my finger over it and plug it so we're going to go to there. our fuel tank pressure. Go Not venting. Make sure it closed.

It's not venting and we should see a steady rise in pressure. Now that we've got the system sealed, we know our gas cap sealed. We've got our purge valve sealed off here now and we should just see the slow and steady uptick and this is you know, not like a you know 100% way to do it. but after a while you start to learn the amount of of pressure increase.

On a you know normal day when your gas Tank's warm and volatile and the fuel's expanding or the vapors I guess and it starts to build pressure. you can kind of see it, just it's very steady it. build pressure here I don't know the words I'm looking for but you'll you'll get it. And um, this will typically mean that there's not not a leak.

Now it could still fail a leak test, but this is just a quick and dirty way to see. You know, do we have a big leak? And then when I remove my thumb from the purge valve here, we'll see it go right back to atmospheric pressure very close to it as we just did. you know? Then I put my thumb back over it and then watch it build pressure again. So uh, when we get a good purge valve on here, our problems will be resolved and we don't have to bust out the smoke machine because we just did it like this.

Oh dang it all, that's what I didn't want to do it I got that? I got that? Put a little fry Lube on there I We're going to trigger the right front wheel here all right. So now we have all of our tire pressure sensors reading here and we're going to go to relearn and we're going to do an OBD relearn here. So that way we don't have to put the car into uh relearn mode which GMS are pretty easy, but this will just go through the process for us. Otherwise most GMS you just do them with the key fob.

This is going to write all of our IDs for us. Once that's done, it gives us the thumbs up. So that's it. So our tire light should be out now we're just key on engine off and the light's still on I don't want to start it cuz I'm waiting for the sucker to cool down.

uh I'll show you here as soon as we're done. We'll take and uh, fire it up. This worked out good. We got one from standard standard Motor Products when the OE fails trust standard uh, not a sponsor but I check with Napa Never any parts available, that's what that stands for.

They did not have a purge valve or a coolant sensor for a 36. GM if you can imagine that. uh, a lot of times on these I like to go OEM but of course with our big Union Auto Workers strike, we can't get get any parts OEM so that kind of sucks. Uh, these things are pretty failure prone.

They're even more failure prone after market. There's statement here when OE fails trust standard. Probably not so true. I think the OEM ones are made by Bosch It's probably an aftermarket.

it's on. Oh no, it's not. Yeah, they're yeah, the OEM ones are Bosch They do pretty well. This one will be back in about a year if we get lucky.

So standard Motor P same same ones if we bought uh Echin from Napa same same brand they make the parts for Napa Electronics the Ean stuff so we'll stick that on there now. Let's see, we'll do this one like that. stick the little metal sleeve in there sh and then put the other rubber here here like so and stick your bold in there so you've got her all assembled like that. Spit on it a little.

Ah, usually the classic spit trick works There she goes. slid right in line up our Bolt wow this your first time fella. There we go. Keep trying little guy.

You'll get it. Don't go crazy with them soon as that baby stops turning. Stop turning. So we plug it in.

Plug it up. Let's see if we still have pressure Actually's still pretty warm. Oh yeah, no. Radiator hoses are pretty solid still.

Oh I Don't really want to make a huge mess. We'll send this here to the stent County Landfill and do our part making the mountain. Uh, we have to pull this off to get to the radiator cap. We should be smart about it and just go ahead and do that so we can take any pressure off it.

So these are pretty easy. You just pull, hold the centers up in them and then the little push nail will come out and you do that about 10 more times here. Get to those and those keep working your way along. You'll have it off in no time.

Sometimes you get one that's stubborn. Get underneath of that little fella. There we go. Well, I'll be I Don't think we need to unhook that.

We just need to get you ready your cap. I'm going to leave those rubbers hooked up on the ends. Mother pear, get out your your General Motors radi your cap removal pliers. Oh must have been just being a puss.

All right. So I just want to take the cap loose and now we're going to put the cap right back on. It's highly convenient how they hide it under the plastic. uh I think it's a 3/4 socket.

We'll see if we can't spin that out and then spin the new one right in without losing a lot of coolant. slash all of it and without burning oursel. There's really not much to see or much that I can show. So I used A/2 in Drive deep socket so it would fit around the sensor.

We probably ought to get the new one first also brought to you by standard, not a sponsor they're from Mexico it says so there's that. That's all she looks like and let's see how we can do this. Am I going to be able to reach in like this? Kind of want to get this figur it out. We'll figure it out once it starts happening.

Oh she not. nothing coming out at all. perfect. Often times if you take the cap off, put it back on.

Granted, there's no other big way for air to get into the engine or into the cooling system. You're usually in good shape and then just be careful with your socket. You don't actually break the sensor. You know the plastic portion of it, so don't have any unusual sideways pressure on the plastic on your socket rather so you want to torque that to factory specs.

We'll come back and do this that here in a minute and it's kind of a pisser to get the connector off cuz it does have this heat shield over it, you kind of got to pull that up, but they don't give you a lot of extra harness and so we're just going to plug it back in here. kind of by feel. I can see a little bit there. get it around there that to stand right where you guys are once you get it plugged in.

got to get the little insulator back over top of it I Know the lighting is not the greatest for you guys, but just put that back on there. and if you gave the dip stick a uh, slight relocation, grab a hold to that and give it a little tug back over and there you go. That's it. We're done.

We're out of here. Hey what you doing I'm back. How'd it go? Are your teeth nice and shiny? Now she's said, my teeth are immaculate. Are you kidding me? No, you want to know what she told me this morning I had a different lady.

oh you had a different you didn't have my lady. no frier I don't like my lady I know she told me that I need to brush my tongue better. we have never had the back of it. Then she pushed it on it.

so I gag Oh that's why you don't brush it huh? That's why you don't brush it. Yeah, you think you know. don't brush out my Thro hole too much. Anyhow, I Now now it's just a matter of putting all these little guys back in.

Oh yeah, I Had to go skip My cleaning today. The lady does my clean I Don't like that lady. man it's rough heavy-handed then. I had to go to Orthod Dinast after that and I've got what they call power chains.

They sound cool, but they hurt like hell. and I can't run any faster. Do anything. Even though there're supposed to be power chains, let's put this baby back on.

Oh gosh dang it. Oh little rubber thing that goes around the oil hole here. they're always swollen. There you go, you got line up there.

What a ridiculous design. GM has always had this where you got to pull the oil cap which conveniently is recessed in a hole and it's always full of dirt and seeds and stuff. Whoever Thought that was a good idea. Fired up tire light is out.

Let's go to trouble. codes here. clear them being she taking off. All right Our coder erased.

we can watch our day. G Co Temperat at 116 118 in Climate Watch that we really need to watch. Don't let her warm up. They made it up to 174 right now I say 172 174 and this is about the time sure where it was goofing up before and it's been nice and steady on the way up so far.

see 176 I'm going to continue to watch this for a few minutes. Oh, we're looking pretty good folks. I think I think we're going to call it I'm pretty happy with it. Back out of here.

I Guess that's it folks. Uh, everything looks good, appears to be functioning. We've fixed everything this lady wanted to fix. All of her lights are out now.

Uh, so we fixed the uh, coolant temp sensor which seemed to be intermittent. um, had the code in OEM data but nothing stored in generic OBD2 which is kind of weird. not going to think about that too much. Um, but we were able to see it fail so that's that's good.

We're able to prove yeah, your cooling sensor is going wonky and it's pretty easy one to change so we just you know, popped it in there and then I let it get up to it's about 194 there last I looked at it and that seemed to be going good. Uh, tire pressure sensor was just a you know failed sensor so not a big deal. There car's got 990,000 on it I think people always ask that. So I'll tell you 96,000 96019 on this little guy.

Um, what else did we do? Oh, and we found the purge valve to be the cause of the small evap leak. Um, so don't overlook that When you're looking at evap testing, read the theory and operation of how and when it runs its small leak test. A lot of these are key off tests like natural vacuum leak detection, that kind of stuff. Um, typically on these when the purge valve fails and it's stuck, you know, wide open, you'll get a code generally for uh uh, like you know, excessive purge flow or Purge during a non-p purge flow event I I don't remember the numbers right off hand I'm kind of surprised that wasn't in there because that did seem to be.

you know it was stuck. Pretty good. Uh, perhaps that was you know, down the pipeline here U But with the coolant sensor failing, coolant sensor is a huge player in uh, your drive cycle monitor. If your coolant sensor doesn't work correctly, it usually will NX the whole drive cycle.

uh and won't run the monitors correctly or at all. So uh, that perhaps is why we didn't have. you know Purge during a non- purge event code or you know, excessive Tank Vacuum or unable to bleed take vacuum. There's a lot of different codes they can throw, but um, GM Evap systems in general in a whole are are quite simple to work on.

They're about as basic as they come, and they're about as faure prone as they come. I Would say they probably not just dissing on GM but they're probably one of the most Troublesome faure Pro and worst EVAP system out there. uh I think Chrysler does a little bit better and that ain't saying much. Anyhow, why don't you guys do me a solad down in that comment section questions.

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