Malfunction Indicator Lamp

My 2016 Prius Two Eco had its Malfunction Indicator Lamp illuminate tonight. I parked it in the garage thinking I would take care of it in the morning. An hour later I went into the garage and it smelled like gasoline. I opened the hood and everything looked fine and no smell of gasoline. I looked under the vehicle and there was no gasoline spill. I walked around the car sniffing and I got a heavy smell of gasoline in the left rear wheel well under the fueling point. Now I filled up my tank a week ago so I didn't spill any recently while filling up. I opened the gas cap to let it vent and then closed it again. An hour later the strong gas smell was still in my garage emitting from the left rear wheel well. I looked over anything and I can't see a leak anywhere but I can smell it. I got worried enough that a pulled my Prius out of the garage and parked it on the driveway away from the house. Why would the Malfunction Indicator Lamp illuminate for a gas smell? Other than this, I drove the car home without any problem and pulled it out of the garage without any problem. Any ideas?

 

Thank you for the info. My Allstate Drivewise® device sent me an email notifying me of a recently detected diagnostics issue for my 2016 Toyota Prius.
"Detected: Sep. 23, 2017 - 12:34 p.m.
P1423 was detected but additional information is unavailable
Severity: Unknown
We suggest contacting your mechanic to explore this issue."
P1423 Toyota Fuel Tank Gross Leak OBDII Engine Light Trouble Code | Engine-Codes.com

 

Got the result back from my local Toyota dealer service department. The diagnostic fault code P142300 is a current code for "EVAP GROSS LEAK" They inspected evap system "NO LEAKS FOUND" Performed Evap Leak Test with Tech Stream "OK" Cleared Codes "Vehicle is operating to manufacture's specs at this time"

They looked at me like I didn't screw the gas cap back on tight. I filled up the gas tank a week before the fault code showed up so the gas cap was screwed on tight for a whole week. It shouldn't work its way loose. My theory is the EVAP Purge solenoid got stuck open and leaked gasoline vapors which I smelled in my garage and in the left rear wheel well.

P1423 TOYOTA - Fuel Tank Gross Leak
Possible causes: Faulty EVAP Purge solenoid
Possible symptoms Engine Light ON (or Service Engine Soon Warning Light) Possible a noticeable fuel odor caused by the release of fuel vapors
P1423 TOYOTA Description This diagnosis detects leaks in the Evaporative Emission System (EVAP) purge line using engine intake manifold vacuum. If pressure does not increase, the Engine Control Module (ECM) will check for leaks in the line between the fuel tank and EVAP canister purge volume control solenoid valve under the following vacuum test condition. The vacuum cut valve bypass valve is opened to clear the line between the fuel tank and the EVAP canister purge volume control solenoid valve. The EVAP canister vent control valve will then be closed to shut the EVAP purge line off. The EVAP canister purge volume control solenoid valve is opened to depressurize the EVAP purge line using intake manifold vacuum. After this depressurization is implemented, the EVAP canister purge volume control solenoid valve will be closed. Read more: P1423 TOYOTA Fuel Tank Gross Leak

More worrisome is my local Toyota dealer service department told me diagnostic testing isn't covered under warranty and they aren't reimbursed by Toyota. They were going to charge me for a diagnostic test until I complained. Has anybody heard of this before?

 

I am always careful to fill using the slowest fuel flow setting when using the auto-shutoff position even though it takes longer to fuel. When it stops, I never try to put in a little extra gas. I place the fuel cap on the holder inside the fuel door and I always twist it tight and make sure it clicks. I think my Prius has a gremlin.