Seeking CEL troubleshooting advice (P0441, P0442, P0446)

Hi all, first post on Tacoma world.

Last spring, I took ownership of my father's 2003 Tacoma Xtracab 4x4, with 2.7L engine. It is a well-maintained, low mileage (109k) truck, but due to 16 years in the Northeast, has some rust (Toyota replaced the frame a few years ago).

Last weekend, the fuel tank strap broke due to rust. This model year has only one rear strap, so the front of the tank remained bolted in place, while the rear sagged considerably. It's worth mentioning that the fuel tank skid plate has completely rusted away.

I replaced the strap with the OEM part, which required jacking the tank back into place. After a couple of driving cycles, the CEL came on. When I had it scanned at Autozone, the following codes were reported:

• P0441 (evaporative emission system incorrect purge flow)
• P0442 (evaporative emission system leak detected (small leak))
• P0446 Evaporative emission system vent control circuit

My questions are as follows:

• Is there likely a single cause that could explain all three codes? I suspect something atop the tank was damaged when the tank was sagging. What should I look for?
• Will I likely harm the truck if I continue to drive until the repair is made?

Thanks,
Andy

 

The charcoal canister is ontop of the fuel tank. You probably ripped out a vacuum line of something.

 

I'm currently in the same boat, although no rust for me. I've heard of people needing to replace the whole charcoal canister, but that is expensive.
Like wolfgang said, check your connections and hoses for any leaks. A vacuum pump might help here. Also, those codes take a few hundred miles to light up a CEL for future reference.

 

Most likely just leaking hoses since you got the small leak code. Best way to find is a smoke test. Next time you take a drive park, turn off engine and slowly loosen the gas cap, you should hear a hiss, if not,you got a leak. Check the gas cap o ring and filler neck seat for signs of faulty sealing. If you hear a hiss the purge control selnoid AKA VSV(vacuum switching valve) may be stuck open or working intermittently. This EVAP system is designed to prevent gas vapors entering the air we all depend on to LIVE. Due to the severity of corrosion your fuel tank and fittings may be beyond repair and need to be replaced. Cross your fingers and hope for a HISSSSSS.

 

You might want to replace the rusted out fuel tank skid entirely.

https://www.summitracing.com/parts/...3g49LKnG30RIf03XnmN5E29Vp_x3m5E0aApZzEALw_wcB

 

The need to replace the EVAP cannister is usually due to over filling the fuel and soaking activated charcoal in the cannister. When the gas punp clicks off never try to add more. If it takes a few hundred miles to get P0441 your purge control selnoid is working intermittently or sticks open occasionally.

 

Interesting I'll have to look into that.

 

For some unknown reason P0441 will often show PENDING on my scan tool after CEL is on for P0420, most often its just the gas cap or loose vac hose but when P0441 trips CEL,purge selnoid or VSV is most suspect and was PENDING the longest distance. I love taking trips in other peoples yotas with my scanner as my excuse for a road trip on their $$ They are just happy to have CEL out.

 

the pending code on the scan tool means nothing more than that error have not met parameters to turn the CEL on. Most evap codes are a 2 trip test with a certain set of operational parameters before that test is run.

 

You are correct. Winner winner chicken dinner!

 

Hopefully this was the correct answer. I inspected everything I could that didn't require dropping the tank or removing the bed. I noticed that one of the vac lines that runs alongside the filler neck (there are two; I mean the one closer to the front of the truck) was disconnected, so I hooked it back up. These lines seem especially vulnerable to being tugged loose when the tank drops, while most of the others connected to the evap system seem less so.

I'll go tomorrow to have the trouble codes cleared and will update after a few days of driving. Thanks to everyone who chimed in.

Lastly, I'm learning that there is a lot of knowledge/experience dealing with the evap system, and it can be frustrating and expensive to repair. Hopefully it remains trouble free after this.

Best,
Andy

 

I added bold to highlight this statement, which I'm curious about. It is mentioned above that the evap system needs to go through two operation cycles to run a test for P0441. In my other reply, I described reconnecting a disconnected vac line I discovered near the filler neck. I wonder if a disconnected line is a severe enough fault condition to trigger a CEL more rapidly? It seems plausible that the tank strap failure, disconnected vac line and evap system DTCs are all related, and rather unlikely that some other yet unknown fault from a few hundred miles ago triggered the CEL two days after the tank strap failure. I'm not trying to be critical of your statement; to the contrary, I appreciate the advice.

Enough speculating on my part...time will tell if reconnecting the vac line resolves the issue.

 

I've seen that one on Summit before. Seems like a a good OEM alternative. Any experience with it?

 

No personal experience with it but several people on TW are running it and give it positive reviews.

 

Back in 2014 I was running into the same issues. I had the system vacuum tested and there were no leaks. I replaced the vsv and still kept getting the same error codes. After speaking to the local Toyota dealership they say my charcoal canister was saturated. (I was topping off my tank every time I filled it. Bad idea). They wanted $1400 to swap it out. They said they had to put it up on the lift, drop the gas tank, yada yada.
I left and went straight to Autozone. Paid $80 for a new canister. Went home and crawled under the truck. I was able to sit up and see the canister mounted over the tank and swap it out myself.
When I did it I disconnected my battery. After I was done with the swap out I reconnected the battery and started it up. No more check engine light or error codes. Passed smog just fine. Hope this helps.

 

Hi all,

I meant to update sooner, but since driveability wasn't a factor with this issue, I wasn't in a huge rush. Anyway, I reconnected the aforementioned vacuum line alongside the filler neck and hoped the CEL would eventually shut itself off. Well, that didn't happen, so after about a week, I bought an inexpensive OBDII code reader from harbor freight. I connected and verified that the same codes originally pulled at Autozone were still showing, then cleared the codes.

After a couple of drive cycles, the CEL came back on, so I connected the scanner and pulled the same three codes that started this ordeal. After a few more days went by, I had the chance to poke around again, and discovered that another vacuum line was disconnected. I discovered this by feel, since it was in a spot that I couldn't see. This was the second of the two lines that run alongside the filler neck. Amazingly, the filler neck itself appears to be intact, so that's a relief. Anyway, I reconnected the second vacuum line, again, purely by feel, and noted that my hand was completely black from what resembled soot, which I'm speculating may have been charcoal from the EVAP canister that leaked out...I don't know if this is possible, but that's what it seemed like.

After a week a driving and several cycles, the scanner says all readiness codes (including EVAP) are set and the CEL has not come back on. I'm remaining cautiously optimistic that the problem is solved and the EVAP system will work correctly for the foreseeable future.

Thanks again for all of your help.

Best regards,
Andy

 

That's great news man. And even if it does come back on, hopefully not, you already have a good grasp on what's going on and possible fixes, etc. Nice work hombre

 

I have the same 3 codes on my truck. What should i do? Ive replaced the gas cap w/ oem from Amazon. Do i need a new charcoal canister or purger valve? Smog is due at end of this month dam California!

 

You should probably start a new thread, since my issue has been resolved. That said, the solution to my problem involved re-connecting the vacuum lines that run alongside the filler neck. I don't understand the system or its components well enough to explain why these lines being disconnected caused the codes, although to someone who understands the EVAP system thoroughly, it would probably make complete sense. Just be wary of self-proclaimed internet experts who claim to understand.

If it helps, I thought this article was a good read...it got me thinking a bit about how to inspect the system.

https://us.autologic.com/news/toyota-tacoma-evaporative-emission-faults

In any event, I suggest you begin by conducting as thorough an inspection as you can, without taking anything apart, for fear of causing further damage. Use an EVAP system diagram to guide you. You may get lucky, like me, and find an obvious, easy solution.

Lastly, EVAP readiness codes are set after two "trips", in which certain operating parameters need to be satisfied. I suggest clearing the codes after you make a fix (gas cap in your case) and drive for a few days to see if the codes come back.

Good luck.

 

Thank you for the quick response.