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Discussion Starter · #1 ·
I put the original gas cap back on (check engine light still on), because the dealer told me my aftermarket locking gas cap was "leaking" ("Stant" brand... sold to me by the same dealer)... Apparently computer code says it's an "emissions" prob., so why then are the traction-control failure lights on too -dealer can't explain other than to say that they're tyed into the check engine light (retard!). Traction control may not be working -can't find a puddle to try to floor-it in so I can see if it's working or not... Hate the traction control anyway, but the light is annoying.
I really don't think it was the aftermarket gas cap since I've had it on the car for the last 3-4 months with no prob....
ANYONE -know what the prob. could possibly be????
 

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I've heard before that if you over tighten the gas cap, it can throw the check engine lights on.. same with not tight enough. Dealer should of turned off the lights and figured out what was wrong before you left.


When there is one trouble code, all dash lights pop on. My guess it's a safety thing to get you into the service department so toyota can protect their rear's.
 

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Disconnect your battery , let it sit for a while (20 minutes) and re connect. It will reset the ECM. Make sure you put the stock cap back on and it clicks. You will need to drive around and let the computer re learn the engine.
 

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FunJunkie said:
I must have a defective sensor in the gas tank, I've driven home with the cap off before in a hurry and no lights or anything.
What produces a check engine light when a gas cap is missing is called an DMTL (detection module for tank leakage) its a pump in the gas tank that pressurized the tank arouns 1-2 psi then checks for leaks using an ahmeter and registers the voltage drop in the pump to maintain the pressure. For this test to run sertain criteria must be met. fuel evel between 15-85%, all OBD2 rediness test must becompleted, coolant temp between eh and so.... If you drive short distances you coul never complete all the OBD2 onboard tests and the DMTL could never run. This happens to people who get their check engine lights cleared then run to the smog station asap. FAIL.

A P0455 (gross leak) or even a P0445 (small leak) can be triggered by very very small leaks, less than .5mm - .1mm
 

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FunJunkie said:
Interesting. you know a heck of alot of good stuff J, what do you do for a living??
I know nothing!

I'm a technician for Land Rover. I see loose gas caps from check engine lights alllll the time.
 

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I've had that light come on once, but it took five hours (of trail running) to come on after a fuel fill-up. I re-capped, and it took over 40 minutes of driving for the light to turn off.
 

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Discussion Starter · #9 ·
Thanks all!!! Great tech knowledge! So next question is are there any locking gas caps that work? I live in L.A., take trips down to Baja, so need a locking cap. The one I have is a "Stant" which I've since replaced with the stock cap...
 

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Re: HELP! check engine light/trac lights on, dealer says its bc of locking gas c

Sean, I've been running my locking STANT for almost 2 years and never had a problem....maybe the one you got was just defective..... ::)
 

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I started having the lite problem after I put in a man-a-fre aux tank emailed them ,still no response :mad: :mad: :mad:
 
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