No P codes. Check engine light came on.

System says emissions issue and points to gas cap. I checked it and it locks and clicks as normal.

Should I just throw a new one on or has anyone else had this issue and solved it another way?

03 Tacoma prerunner 6cyl 2WD 3.4L automatic

 

The fuel cap is the cheapest and easiest thing to do. Get a factory cap from the dealership and drive it around for a few days to see if it is fixed.

 

I finally got a new OEM gas cap and installed it. The check engine light would not go out after a few drive cycles (I read somewhere that it could take awhile to clear). So I disconnected the negative side of the battery waited for a couple minutes and hooked it back up. Check engine light did not come back and this is now the second day so I think we're good.

 

Some codes are self clearing while others require a scan tool to reset. The programming logic for what, when and why a CEL comes on is a black art and changes from year to year and model to model. Some drive monitors are 2 drive cycle monitor, others are not… on later vehicles with emission issues and the code is a “permanent” code, it might take 15 drive cycles to clear. Hope she stays “fixed”.

 

Okay , now for the UPDATE:

Note: after reading the AutoZone readout more closely I discovered there WAS a code:

P0456 Small evap leak

Check engine light came back on about 5 days later. Took it to a local mechanic who did not diagnose but cleared the Check engine light. 2 days later the light came back.

After watching as many YouTube videos as I could find on the code, I began checking all the hoses. One of them had a decent size tear and another just small cuts on the end. I plan on replacing both.

Mainly, I did remove the purge valve/selonoid and tested to make absolutely sure it was sealed tight, meaning, I wasn't able to blow air into nor suck air out of it. Thus eliminating it as being the culprit.

I looked at diagrams some of you posted here and was not able to find either part. Attached are some pictures in the hope that someone will be able to identify the part number for the 2 hoses.

The 1st hose is roughly 3 1/2inches and is attached to a hardline on the selonoid end and attached to the intake and resting on top of the top plenum.

The 2nd hose is just below the purge selonoid and is attached to the hardliners coming from the gas tank and attached to a platic

 

Box on the other end.

Excuse the separate posts as this new, refurbished Ebay phone acts up sometimes.

 

2nd pic

 

In the 2nd pic the hose is just above the battery and shaped like a curved 90degree

 

1st pic - the hose is on the top left

 

Have you tried looking them up on parts.Toyota.com?
https://autoparts.toyota.com/products/product/valve-evap-service-port-7773906010#popup-1

 

Evap codes are the bane of all gas autos… do you live in a state that requires smogging?

 

Did you look all around ON the hoses?
Part#'s are on them a lot of times

 

Yeah so I've been told. Yes I live in California. I am almost sure it is the small 3 1/2" hose. If it were the cannister selonoid there would be a different code. One of either a medium or large evap leak

 

Bkhirtacos- I will pull them and clean up to see. Good suggestion..I hope I don't rub off the writing in doing so

 

Clean gently. Too harsh a chemical may wipe it off.

 

Copy. I will use a mixture of warm to hot water and dish soap

 

Ok, the reason I asked is that the monitors for evap are notoriously difficult to complete. It is better to have them be completed before you pay for a smog only to have the shop say you have to pay a second time after the monitors have run. The evap monitors are what are referred to as 2 trip monitors meaning that the PCM needs to see 2 separate trips. A trip is defined where the PCM has been sitting a minimum of 8 hours without a “key on” signal plus the fuel tank between 1/4 and 3/4, 3/4 is better because there is less air space to form the vacuum required for the test… I think there is a third condition but I am having a brain fart atm. It sounds like the monitors are running OK for you as the CEL popped.

 

Good stuff. You know your 5VZFE

 

It needs to be a cold start so the outside air and coolant temp need to be within 15 degreess I think. It also needs to run for long enough for the purge valve to open to pull a vacuum. From there when it shuts off it seals the system and monitors pressure. If it sees vacuum decrease it will throw a leak code depending on the size. If the tank doesn't reach vacuum during the drive it can't run the monitor.

 

Thats it… thank you for that, like I said a brain fart.

This isnt just for the 3.4, it is for ALL vehicles manufactured since 1996.