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2019 Toyota Highlander Hybrid: Check engine, gasoline in charcoal canister, but why?

I have a 2019 Toyota Highlander Hybrid with 4000 miles that one morning this week had an engine sputter (as if the engine was missing somewhat) immediately after starting and 20 minutes of driving later had the Check Engine light go off. I checked the gas cap and it was fine, so I took it to the dealer as instructed; during the 30 minute drive to the dealer the engine ran fine. The dealer tells me that there is gasoline in the charcoal canister and it must be due to my overfilling the gas tank and thus is not covered by warranty. I never top-off the tank and the last time I filled up the car with gas was two days previously, after which I drove it for 30+ minutes home and had no problems. The issue started two days later first thing in the morning.

Is it a reasonable story that without topping off the tank, I somehow overfilled the tank to the point that it flooded the charcoal canister? Or is there another potential explanation? Could the overfill check valve potentially play any role - or anything else? Thanks to all for your help and thoughts.

No.

The Onboard Refueling Vapor Recovery system doesn’t allow packing or overfilling of the gas tank.

The system has a valve called a ROOF valve. Roll Over-Over Fueling valve.

The EPA knew people would try to pack gas tanks so they asked the auto makers to come up with a way to prevent this happening. Because if people were able to overfill the gas tank where it damaged the charcoal canister, it would defeat the purpose of the EVAP system.

Go back to the dealer and ask that they fix the EVAP system under the emissions warranty, or you’ll have no choice other than report the dealer to the EPA.

Tester

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Maybe the over-fill valve failed and at the same time period the gasoline pump auto-shut-off switch failed, which juiced your evap canister. . But this purported scenario all seems rather unlikely. My guess is there’s a problem w/your Highlander’s purge valve not opening when it should. that valve is supposed to open and allow fuel vapors stored in the canister to vent into the engine and be burned there. It opens when driving at road-way speeds. If it never opened for some reason the canister would have no method to vent and could build up gasoline in it over time to the point it was saturated.

Either way, it’s a warranty issue. Raise hell and call Toyota corporate if necessary. Look in your owner’s manual for the info on where to complain.

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Thanks all for the quick responses. This was great advice! After asking the dealer about the roll-over over-fill valve, the next I heard was that Toyota Corporate was involved, directed the dealer to further test the valve (including filling up at a local station), and they determined that the valve may be sticking. They agreed to replace the valve and canister under warranty. So hopefully problem solved! Thanks for the very timely advice - it made a big difference.

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Make sure they reimburse you for any money you spent the first time when they said it wasn’t under warranty.

And keep an eye on this dealership service department. In my opinion, they were either not ethical with you or they were ignorant of the design that doesn’t allow overfilling.