Check engine light due to gas cap

@shifty`

Thank you so much for the time you've taken responding to this issue. Very kind of you.

What I'm seeing is a 'whack a mole' scenario where one thing gets fixed only to have something else need replacing. Given this scenario, it seems $$$ prudent to just let it be. Hairline vacuum leaks are not affecting the performance of my vehicle, nor do they keep Tundra from passing smog check.

Clearly, Toyota (and other manufacturers?) did their customers a disservice sending these tiny leak signals to the check engine light, which should be reserved for bigger more serious issues. There should be a separate emissions system light to deal with these tiny insignificant emissions leaks.

The check engine light on my Tundra has been ON for 20 of the 19 years I've owned this truck. I have learned to live with the boy who cried wolf... by simply ignoring him.

Again, thank you very much for educating me on this issue. If performance problems crop up, then I'll revisit this issue armed with knowledge from our discussion.

 

I went through that on my wife’s suburban. Started by repeatedly spitting fuel back at me and shutting off the gas pump when filling, then the slow evap leak code. Replaced both the cannister and the purge valve but CEL remained. Cannister bag was gone and lots of tiny charcoal pellets came out of it. Took car to shop and they said the pellets had gotten into fuel tank and replaced fuel tank. That didn’t fix it either. Finally found little carbon pellets were trapped in the solenoid that controls the vacuum from the manifold - apparently it sucked in some pellets. Replaced that but light came back after short time. Found I had to repeatedly clean out the pellets with a wire about 10x over the next few months before I finally stopped getting the CEL. It’s all part of the federally mandated emissions stuff.

 

@bfunke

Thank you for chiming in on this discussion. You said "Cannister bag was gone and lots of tiny charcoal pellets came out of it."

My question - was it the OLD cannister that spewed out all those charcoal bits, or the NEW cannister you put in? I saw online these charcoal cannisters can cost $300!

 

@w666 @dt325ic

Thank you both for you contributions to the discussion.

I will add your 'culprits' to the list of possible suspects.

(That mention of 'filler tube' was like a walk down memory lane, I think I heard that one back in 2006)

 

I just checked and it looks like if it was the charcoal canister/cannister there would be a special CODE for that. Is this true?????

 

EVAP issues can always be whack-a-mole and a lot of people choose to throw "likely culprit" parts at the problem rather than either (A) using the most basic tests to expose the likely culprit, or (B) taking a second to understand the system, look at the components, and use logical deductive diagnostics to solve it. For small-leak situations, like I said, most people just smoke test and find the leak, it's that easy, kits are on scAmazon for like $90, maybe less. This is very approachable even for a novice home mechanic if you've got three or four brain cells to rub together.

There's a very strong likelihood the shop that smoke-tested your truck saw smoke around the gas cap, and thought "oh shit - bingo, it's the gas cap!" because they weren't aware of the TSB, and would never think in a million years that the fuel filler neck being cracked or damaged was the problem. The OEM replacement filler neck, when ordered through Toyota Parts website for pickup at my local dealership with their applied order-online discount, is around $75. Not outrageous, and probably a 30 min casual job while drinking a beer, if your VIN is clearly impacted based on what's in the TSB, this has probably been your issue the entire time, and you can solve it quickly, cheaply.

Part for standard bed trucks: https://parts.toyota.com/p/69343056/772010C050.html
Part for stepside bed trucks: https://parts.toyota.com/p/69343154/772010C060.html

A couple of nearby dealerships have it. The cheapest price I could find picking between the three local dealerships was $72. If you walk up to the parts counter and order there, most dealerships don't give you the discount, you pay full MSRP. Still, MSRP is only like $90, but I grew up with less means than most and I'm admittedly a bit of a cheapskate as a result.

Not necessarily. There are EVAP codes specific to the cannister itself, like if I recall correctly, if it's at "end of life", i.e. it's not measuring as being effective, like it's saturated with vapors because something else is wrong, pretty sure you can throw a code on that on some vehicles. Haven't heard about it on the 1st gen Tundra, though. I'd need to look in the Toyota field service manual and search for "charcoal" or something to see. There are some vehicles where you can supposedly just pop the charcoal canister off and vacuum it out, then reinstall and you're back in business.

Really, the purpose of the charcoal and canister itself is to capture unburnt vapors so they're not released to the atmosphere. To do that, it needs to tie into the fuel/air system, and needs to have a place in the vacuum pressurized system, and a way to purge. If that canister is cracked, or a line pops off it, you can see this. If the charcoal bag rips as @bfunke mentioned, it could clog up the purge valve, but you can force the purge valve to open and vacuum it out. If the canister can be popped out, this is easy enough to check, you can also throw a vacuum on it and see if it's clearly leaking.

Like @bfunke mentioned, there's obviously some comical things to go wrong, and unfortunately most people (hell, many mechanics even) don't fully comprehen how the EVAP system fundamentally works, so they'll throw shit at a wall and see what sticks, doing stupid shit like replacing a gas tank because they think some charcoal landed in it, or charge $150 to replace a gas cap. To make matters worse, EVAP systems generally have the same goal and fundamental operation, but how they achieve it can be wildly different between brands, some OEMs operating backwards from what other OEMs use.

There's a lot of small, simple-enough stuff you can do - some free, some costing a few bucks - to diagnose the codes. The bad part about having your check engine light on is, when something else fails, something which could be more serious, you won't know. There's an advantage to fixing this problem and getting rid of the light. If it were me, I'd start with comparing your VIN to the TSB's list, and if your truck is impacted, replacing that fuel filler neck. The part is cheap enough, Toyota has warned this is a known issue, and it may just solve your entire issue. If not, I'd start looking at the canister itself, the purge valve.

If none of the above solves things, which I think the new filler neck probably would, if there's a way for you to actively monitor it while driving (safely), could be worthwhile to make sure your fuel pump isn't showing signs of fatigue...

To this point, if the cannister itself isn't cracked or damaged, you typically don't need to replace it, you can just re-pack whatever was in it - usually a bag of charcoal pellets, often some kind of cotton or similar batting. The charcoal can be loose, sometimes it's in a breathable mesh baggie. For those packed with cotton, it's possible for the cotton to get saturated, replaceing with similar cotton batting is a viable low-dollar fix as well. But really, junkyard pull is totally a legit way to handle this with EVAP parts. I've done it on plenty of trucks before with the cannister and the purge valve. I'll usually try to find two on the yard in case one is bad, in all but one case both were good, and I sold the spare on eBay to make a few bucks, adding to my truck slush fund.

Anyway, long ass reply just to say: You have a very likely culprit in front of you in that TSB. This problem can be solved without using a mechanic. There are a lot of inexpensive and/or free ways to diagnost/solve it. You can do this!

I know a lot of people like to bash on this stuff. They'll spend more time bitching about it and how it's forced on everyone than it actually takes to understand the system and solve the problem. I get it ... but I'd rather solve the problem than piss and moan about regulations and whatnot. It's there. Has been for decades and we can't change that now. EVAP systems let us keep our gas cars that much longer and stave off electric for another couple of decades.

 

I actually came online to edit my reply to not sound bitchy, sorry you had to see that.

Tundra's VIN middle numbers are 34103, your nomenclature for 2WD-V8 says 3#1#4???

Clearly, the first step is to buy a $40 gas cap (cheap first step), disconnect the battery, drive around, if/when the check engine light comes on, stop by auto parts store, get a fresh set of codes, etc. I'll ask the mechanic at the 100k service what he charges to just do the smoke test.

... and go from there...

EDIT Where's the best place to get a really really really good Toyota Tundra '03 4.7L V8 2WD SR5 GAS CAP?

 

I didn't read anything that seemed bitchy to me...

Basically the "#" just means it can be any number in that position, really. If you're confused about whether it applies to your truck but don't want to post your VIN publicly, feel free to inbox/PM me with it if that's cool.

Honestly? Anywhere except scAmazon, fleaBay or WallyMart online, because you're liable to get a fake.

RockAuto is an option, or just order direct from Toyota Parts, for pickup or shipping from a local dealership. Your truck's fuel/tank page is here, your cap part number is 7730047010 (old p/n style: 77300-47010) and you can look at pricing and setup purchase/pick it up at a discount from your local participating dealerships here. My local dealerships are showing it at around $32+tax if you order at the parts counter directly, or $23+tax if you order it for pickup via Toyota's website.

 

Toyota Parts website not working - any other suggestions?

 

Dunno what to tell you, it's working for me when I click the link - maybe you've got an ad blocker on your computer and/or network that's not letting the forum link jump?

You can also just try copy-pasting this website address into your browser: parts.toyota.com
In the search box, copy-paste this part number into the search: 7730047010
Then pick a dealership to order from, to see the final price, and order.

If you don't mind paying $30 plus or minus a couple, you could also hit up any local dealership and give them that part number, they'll grab it for you.

I can't find any other online retailers selling this part legitimately. But if you can't hit that website, McGeorge Toyota's website is another folks on this site use: https://parts.mcgeorgetoyota.com/

It's only $21 there but you gotta pay tax + ship, so maybe close to a break-even on local pickup.

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Bizarre, the Toyota parts website won't let me change the zip code - it's stuck on 89044. No worries, I'll hit up the local dealer, call first to make sure they have it in stock. I have to run an errand over that direction, won't be before next week. I'll disconnect the battery and reset things. Probably won't hear from me for a couple weeks until that light comes on again.

Thank you, @shifty`

 

That zip thingy is weird for me too. Like, when I click on the zip code box, it doesn't remove the zip code it detected you're in. I hafta click on the box, then start pushing numbers and it lets me type in. Maybe it's just because I'm using Google Chrome most of the time. Dunno.

 

I got mine from rockauto. Cleared my code and hasn't come back.

 

@shifty`

UPDATE good news it has been one month since the mechanic replaced the filler tube per Toyota Service Bulletin. We topped it off with a new gas cap to boot. Smoke tested the emission system. Reset the system (is this a fancy way of saying “disconnected the battery”?)

One month later, Check Engine light has not come on!

Tundra running great!

 

Thanks for coming back to update, it's super helpful to see this kinda feedback. And it reminds me I need to link up the TSB for this in the Gen 1 information dump sticky thread...

Hoping that's the silver bullet, and I'm not surprised if it was the problem all along!

"Reset the system" = Clearing all stored codes from memory. Can either be done using a code reader tool, or remove the negative battery cable for 10 minutes. The ECU doesn't seem to store codes and other params in NVRAM or anything, so wiping power for a period of time is all you need to force the car to forget what problems it had (similar to what good beer does for me!) and make it re-learn its optimal running state, go through system checks, etc.

 

I bought Tundra at an 'end of 2003 clearance' - October 2003. The TSB came out December 2003.

Chalk it up to not driving Tundra enough, being used to seeing that light and doing nothing about it.

I'm probably the last 2003 Tundra owner to get this fill tube replaced.

Thanks again, @shifty` you provide a wonder service to this board.

 

I bought a gas cap from them. That’s how they got me

 

Glad to hear this appears to be fixed. Nice stick-to-it-tiv-ness.

 

Apparently not. I recently had the P0442 CEL come on on my 2003. Cranked the gas cap tight to be sure and cleared the code. The next time I filled up with gas I thought I saw a drip, but thought most likely it was a pre-existing gas station asphalt stain. Filed it away as a data point tho.

Sure enough, the CEL came back on. Crawled under today, saw what seem to be cracks in the fuel filler neck. Looks like my VIN is in the TSB range, and I don't think the PO replaced it, but I'll check better in the morning.

Since I'm leaving on a 1000 mile business trip and this code doesn't seem to be life or death, I'm wondering if I should a) just ignore it, or b) put some JB Weld plastic bonder on the cracks. Or gorilla tape...?

Aside: wasn't sure what MIL meant in this context, had to google to make sure it wasn't "Mother-in-Law" as in, "that damn engine light on my dashboard is as annoying as my mother-in-law".

 

FYI....T-SB EG019-03 mentioned earlier in this thread, which affects certain 03-04 SC(standard cab)/AC(access cab) Tundras, was superseded by T-SB-0003-11 on 01/05/11.

T-SB-0003-11 attached....

 

If you have a rattle can of Flex Seal and it's easy enough to get the neck outta there, you could hit it with that also. If not, just wipe it down with alcohol and hit it with rubber cement on a brush. EVAP being what it is, it'll want a sealed system, I don't know that it'll really affect you much.

I rolled back and updated my earlier post to link forward here. Thanks for the update!

 

Is this a crack, or just an intentional gap? And if a crack, would this be something that could cause the P0442 code?

(I realize that without removing it for inspection there are potentially cracks elsewhere, too.)



Didn't have Flex Seal, but I did clean it up, wiped with alcohol, and put some JB Weld plastic bonder on (yes, that is JB Weld...) and worked it into the crack. Will try to remember to report back if the CEL goes out.

 

I love when it gets worked into the crack.

Anyway, I can't tell if that's intentional or not. The fact there's a seam from a mold perpendicular to it nearby, I'm struggling with why you'd have a seam in your mold right next to a split, which makes me think that's potentially a crack. But without seeing pics from another '03-'04, I'm not confident in saying.

 

@NomadicFrog Did this fix work? I have a similar crack in mine along with )442 code

 

Your truck year has a TSB out for this specific problem. More information is in the megathread. Here's the pertinent text from that thread, download the TSB and follow its instructions to fix with the updated part:

Cracked fuel filler neck TSB for 2003-2004 trucks. See here. Causes P0441, P0442, P0446 codes.
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Even if some glue fixes the problem, it's gonna crack again somewhere else eventually. Given how Toyota is discontinuing parts for our trucks like crazy, you should probably order the updated/corrected part and install it while still available.

 

THanks, I checked the VIN it doesn't fall into the range. Its slightly higher if I understand the post correctly. My second # is 6, making it higher, correct?

ETA: Looking at it again, maybe I'm stupid. Does the first batch of numbers matter? If its the last 6 numbers I'm lower. Does a TBS mean its covered for a repair by Torota?

 

TSB just means Toyota is aware of an issue, it's a technical service bulletin which defines some work they recognize as being necessary due to a condition they've encountered as "not just a one-off fluke". If you catch it in the warranty period, I've had them do the work for free if it's a component that's typically covered under warranty.

For the Effective VIN, I either get this right away or I don't.

IIRC, the value of the "#" doesn't matter, I think the first one, digit 7, is for the model type, and the other in position 9 is a 'check digit' to validate the full VIN#.

The last 6 digits of the VIN is the sequence of trucks produced that year, and 2 digits after the "S" is the last digit of your year. Like, from that chart, if you have a 2003-2004 truck that's a "STANDARD CAB" or "ACCESS CAB", and the last 6 of the VIN is 440333, and the last 6 of your VIN is a lower number than that, you're impacted. Basically they're telling you, in that change chart: If your truck was made BEFORE that VIN sequence number (the last 6) and the other parts of the VIN match, you're impacted.

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Thanks shifty. Definitely not under warranty lol. I have a Crack very similar to the one Posted above. I'm going to patch it and see what happens.

 

I had the code once myself, thanks rubber-eating rodent... Of course this was on top of the hose, took a minute to find it.

Glad you got yours figured out

 

Was the code 0442? That doesn't exactly look like a small leak lol. I patched what I thought was my leak yesterday. Truck passed inspection but 0442 code came back this morning. At least I got another year to fix it