Come along as I have a look at a customers 2005 Buick LeSabre that came in with a very small EVAP leak. This was an easy one as long as you know how the EVAP system on a GM works. They are perhaps one of the simplest in the industry.
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Hey there viewers! Welcome back to the South Main Auto Channel that's a 2005 Buick LeSabre It's got the big Three, Eight Money lights on all Tails hooked up. it's over there scanning doing its thing. Once that's done, we'll see what Coda has in it. Probably an EVAP code because it's a Buick and not a whole lot of things go wrong with these. but lots of evap troubles so we'll find out and then we'll see what's wrong with it. I wasn't too far off was I All right. So what do we have here? A large evap lake? So your classic P0455 that was the only code in it oddly enough. So we're going to pop into the control unit right to the powertrain. We already know what the code is, so let's go into Live data see if we can learn something here and then we'll go into evaporative admissions. It'll be a good place to start. We just want to see does our fuel tank pressure sensor work. There's a 1.47 volt one and a half, but close to where it should be. The EVAP plot history is from a weak vacuum. It'll release that tile the PCM perceives. It shouldn't really be anything else in here that we need to know about. So let's think about this. We have a large leak that could be caused from. you know from weak vacuum from No Purge function. it could be caused from an actual leak. It can be caused from a missing gas cap. you know, lots of lots of different things. but but the PCM is actually looking for is it closes the canister vent valve so you know that'll have to close. Then it will draw a Purge on it with the purge valve and then it needs to see change in fuel tank pressure. So we have three items there that need to work. So let's do this. Let's back out. We're gonna go to some function tests here or active test. maybe go to engine and then we want to find the cancer bent valve. We want to see if we can hear it and noisy in here today, but let's see if we can hear it I don't know if you guys can but I hear clunking away back there. so we turn it on and essentially if the system were sealed on a warm day like today, it's I don't know. First week in November but it's still pretty warm out. it's in the 70s today. I Think we would see this building pressure. You know our fuel tank pressure would change with the canister vet valve clothes. you know, some natural vacuum or natural uh leak detection. it would you know start to increase as the fuel is volatile but we can see there's no change there. We definitely hear it so that's interesting. Let's uh, take and start it up real quick. Okay let's close the vet valve. Foreign ly getting drawn into a vacuum but our Purge is not even turned on so let's open it. we go back to atmospheric pressure. Purge valve. is not on. We should have no vacuum on the system. Closed the vent valve, we shut the back door, but the old Purge valves up there giving her a little sucky. sucky because we're drawing it into a vacuum. So there. Just like that, we diagnosed it right from the driver's seat. it's a on hands. Let's go up and give it a whack with a screwdriver. Well there it is down there. easy. There fella appears me, looks original to me, nice and Dusty we're gonna give her one of these like I Say right now you can see that it's still trying to pull it into a vacuum. However, it's not being commanded on so it shouldn't fixed it. Look at that. it's no longer drawing it into a vacuum because we closed the vent valve so it's no longer bending. But we can see that it's not drawing it into a vacuum anymore. But look at that. it will finally. Hey, we get every one of those so that's all it needs is the canister purge valve. So let's do this. Let's turn this off. So now we're back bending to the atmosphere. Let's shut the engine off. Stand right there. Now we're going to key back on. So we're key on engine off I Think it's in the 70s. It's 68 in here. It feels like it's the 70s. So now I'm going to close the vent valve. So now that it's closed, my assumption is it's going to start to build pressure. but I could be wrong because it may not be quite warm enough. The reason it wasn't before is because our vet valve here our purge valve was stuck open. Now we still may have other leaks because it is closed, but I don't see a rapid increase in pressure. I'm going to order a purge valve because we know it's bad. I'll leave that closed here for the few minutes while I do that and we'll come back and check to see if we have an increase in pressure. All right. I Ordered one from Chevrolet I won't have it until Tuesday today's Friday So the only one Napa had was the Dorman one and want to play the stupid game if that one's been on there since 05. We're just going to get OEM because it's only eight dollars more than aftermarket so we'll get the brand new. OEM However, the good news is in a few minutes it took us to call a Chevy If I can get this out of glare, you can see we do. We are starting to build pressure albeit not a ton but some. so when I open this, it should go back in to you know, zero atmospheric. So just open and we're back to atmospheric pressure. So that tells us a lot. You know might not seem like much to you guys but it tells us a the system is sealed, it works perfect and B it's it's sealed and works perfect I Don't know what all it tells us. it tells us that it's sealed and it has the ability to to build pressure on its own even though the car doesn't utilize that as any part of its. Diagnostics We can use it as our Diagnostics because we know that the car indeed has no leaks in the EVAP system. but we just have a crappy purge valve because we could see that and we figured this all out in like a minute. So that's it. We just, uh, we move on with our life. Now we'll put the cover back on, we hand the customers keys and say Hey you come see me on Tuesday fella and I'll pop that on for you out in the parking lot and he's happy and I'm happy and you're happy at least I Hope you're happy folks. Uh, so kind of a Cheesy video easy you know Diagon on this thing and I hope it kind of gives you guys at least a little insight. If you're working on, you know GM or any other evap systems. I mean GM probably has the number one, most failure prone EVAP system on the planet and they do. I Mean it's just a matter of fact, doesn't matter where you live, all the EVAP systems on these things are broke. But beyond that, the best part about them is they're a really simple system to work. However, we get a ton of these cars and trucks in from other shops which I don't understand to fix evap problems. and it's there's only three components. Uh, kind of. I mean you have your Purge your vent, your fuel tank pressure sensor. All three of those things have to work and then the system has to seal and that's about it and you know it can't be plugged. You know there are some Oddities that you'll run into now and then. but if you can fix these, I mean these evap systems are very similar to the Ford and Honda and Nissan and Mazdas and you know the only thing they're kind of different from is Toyota. They got their own little nut job thing that they do. but other than that, these are pretty simple systems and you can find out a lot of information without even putting the car in a lift without busting out a smoke machine. Really? without getting your hands dirty. Uh, just by knowing how they work. Looking at the data and you know how can you apply what you have and power in your hand, you know, with a scan tool or whatever and figuring it out. So hey, that's I'm not trying to sell you on it. However, if you'd like to buy yourself an ALT Just kidding, forget about it. go in that comment section questions, comments, Concerns: Instinct Facebook You guys know what to do. Just my reviewers. but I can do it. You can do it. Thanks for watching.

96 thoughts on “Buick lesabre: quick dirty diag from driver seat”
  1. Avataaar/Circle Created with python_avatars calholli says:


  2. Avataaar/Circle Created with python_avatars Jeff and Rachel Schwartzel says:

    Eric, Thanks for your videos. They are enjoyable. Can you go to the chalk board and draw a typical vapour venting system complete with solenoid valve and purge valve. I am having a hard time to understand how the whole system is put together and how it operates. I would appreciate a Purge System 101 lesson. Thanks

  3. Avataaar/Circle Created with python_avatars William T. Musil says:

    Hiya Eric

  4. Avataaar/Circle Created with python_avatars Captain DeStructo says:

    I'm happy.

  5. Avataaar/Circle Created with python_avatars tv says:

    Good stuff thanks

  6. Avataaar/Circle Created with python_avatars Joe David Zuniga says:


  7. Avataaar/Circle Created with python_avatars Travis Jansma says:

    I have a 2002 Buick Lesabre with the same issue. Replaced purge valve and didn't fix issue

  8. Avataaar/Circle Created with python_avatars Lionel Vasquez says:

    Great video. Very informative.
    You did one a while back where the GM fuel tank pressure sensor was the culprit. So this video was another one that helped me understand the EVAP system better. Thanks

  9. Avataaar/Circle Created with python_avatars abruptly blunt says:

    3.8 is a great engine, it's a shame that in the FWD application the rest of the gm drivetrain is garbage………

  10. Avataaar/Circle Created with python_avatars M Lieser says:

    Dorman products. For those technicians who love their job so much they get to do it twice.

  11. Avataaar/Circle Created with python_avatars joeylj7210 says:

    Awesome work Eric O.!! 👍👍

  12. Avataaar/Circle Created with python_avatars timothy hynes says:

    At least he had a 3800 , that was a great engine

  13. Avataaar/Circle Created with python_avatars CS says:

    I agree with Dans learning curve, nothing cheesy here! Your a great technician, and if I lived near your shop, you would be the only person that would touch my car!!! Thank you for the videos!

  14. Avataaar/Circle Created with python_avatars shay stern says:

    not cheesy, good job

  15. Avataaar/Circle Created with python_avatars Pat Jago says:

    I’m getting older but am happy to report that my purge valve isn’t leaking (yet)

  16. Avataaar/Circle Created with python_avatars Meatball Magoo says:


  17. Avataaar/Circle Created with python_avatars Posh panda says:

    Good, do I don't know what it means. Do I have one of those, has never showed up…

  18. Avataaar/Circle Created with python_avatars Mailman Joe says:

    Everyone seems to have a love for those big 3.8's. 😊

  19. Avataaar/Circle Created with python_avatars SoLo says:

    "Buick Dealers hate him", Find out the secret with this one simple trick".

  20. Avataaar/Circle Created with python_avatars Ronald Anderson says:

    Yeah, at the outset I was like looks like summer, is this a current video? It sure is winter up in the Rockies man. any day now.

  21. Avataaar/Circle Created with python_avatars Jim Mizzi says:

    Good engine, in Australia we had a razed aluminium intake manifold and RWD🇦🇺

  22. Avataaar/Circle Created with python_avatars Jay - In - Az says:

    Really learning a lot from you, Eric. Thanks

  23. Avataaar/Circle Created with python_avatars CAM NEILSEN says:

    Hell I was getting my cheque book out to buy somethin' ,you sweet talker Mr O !

  24. Avataaar/Circle Created with python_avatars mohamed mutrif says:

    Hi Eric, I'm a big fan of you, could you please make a demonstration video on how the EVAP system works and how to diagnose it?

    Thanks in advance 🙂

  25. Avataaar/Circle Created with python_avatars LMacNeill says:

    I would love to buy myself an Autel — but the price is just a bit too steep for a DIY weekender like me. I wish the cheaper OBD-II tools had bi-directional control like that, so you can command things to turn on and off to help with diagnosing a problem. Unfortunately it's $1,200, $1,500, or even as much as $1,800 to get a tool that does that. Worth it for a full-time shop. Not worth it for the DIY'er.

  26. Avataaar/Circle Created with python_avatars 300DBenz says:

    No effort diagnosis for No Effort November. 👌

  27. Avataaar/Circle Created with python_avatars zackary mcclain says:

    hp tuners can permanently fix these evap codes, Just sayin.

  28. Avataaar/Circle Created with python_avatars Peter says:

    Got a 2001 lesabre with a gas cap loose on the message center and a 440 code, tried a brand gm gas cap a brand new chant cap but still get the code and message.

  29. Avataaar/Circle Created with python_avatars Deplorable Constitutionalist says:

    if you were going to chase an evap leak on your jeep 4.7 how would u go about that and where would u begin?

  30. Avataaar/Circle Created with python_avatars Vic Ferrari’s garage says:


  31. Avataaar/Circle Created with python_avatars wyatt1153 says:

    Bobs your uncle.

  32. Avataaar/Circle Created with python_avatars RAEL says:

    "The only code in it" Pretty good car I'd say. 2005 ? Yeah, pretty good. I had a '94 Pontiac Sunbird, of all things…….had it for 200,000 miles with VERY few issues.

  33. Avataaar/Circle Created with python_avatars Ozzy Krahn says:

    i always learn from your videos

  34. Avataaar/Circle Created with python_avatars twwtb says:

    I'm happy.

  35. Avataaar/Circle Created with python_avatars Xombi Xombi says:

    good bet, thank you.

  36. Avataaar/Circle Created with python_avatars Huntnfishnuts says:

    Toyota evap systems are just on another level of over engineered overcomplicated nonsense 😝

  37. Avataaar/Circle Created with python_avatars Yawwee Shalimar says:

    Since you only did a quarter of the work, did you charge the customer a quarter of the labor/diagnosis/removal/replacement cost ??? Inquiring readers/subscribers would like to know !!!!!! 🔍🔎❓❓❓👍

  38. Avataaar/Circle Created with python_avatars Michael Clarke says:

    When working on my cars, I’ve found myself muttering things under my breath such as “come on, baby!” when I’m struggling a bit and. “There’s your problem, lady” when I make a discovery. 😊

  39. Avataaar/Circle Created with python_avatars Guy Smiley says:

    I miss my old Bonneville with the 3800, that motor was such a gem. Sure it'd eat coil packs sometimes and the intake manifold gasket was perpetually leaking but the mechanicals of that engine were just incredibly rock solid. I wish I could buy a car with one in it today, honestly.

  40. Avataaar/Circle Created with python_avatars robert richardson says:

    But I don't want to forget about it… I want to buy the Autel scanner, or the Topdon with the oscilloscope if I can afford it. Lol Great video, we always need a refresher on some of the diagnostic processes you do!!

  41. Avataaar/Circle Created with python_avatars C V says:

    So you're telling me parts cannon? 🙂 3 shots max.

  42. Avataaar/Circle Created with python_avatars John h Palmer says:

    I got the money light on again on my 03 Mazder. Yes, the classic P5 with the 2.0L inline 4 pot. previous codes were the P0455, the classic P0090, the classic P0660. Now, I have no idea what, except that it could be the same things as I've not dragged out the old scan tool to see and then clear, it did that on the first go ust came back on a few days ago after clearing and it remaining off for about a month without any doing anything to it.

    Anywhoo, if it is those codes, suspect it may be the purge valve that has gotten intermittent. It only has, 195K+ miles on it and occasionally smokes upon startup, and clears up pretty quickly,. once moving after sitting for several days. Then again, it could be a liking fuel injector but who knows? car still runs fine otherwise.

  43. Avataaar/Circle Created with python_avatars paul oneill says:

    hi great work as usual, this may sound silly but what pointer are you using on your autel i cant seem to find one that works and my fat fingers are frustrating me 😁

  44. Avataaar/Circle Created with python_avatars Raving_107 says:

    What a coincidence, i did the same thing on an 02 earlier today.

    Does the autel have the ability to close the vent valve and control the purge valve at the same time? I can do that on our strapon scanner and its very useful for diagnosing evap problems.