Fading check engine light
 

2018 Limited - 22K miles

Washed, drove all morning on errands, went to start it later and it wouldn't turn over. All the lights etc were fine. Tried a few times - ended up pulling the batter cables and let it sit, attached back - started up with no issues.

Drove to Home Depot - turned it off and the check engine light started to fade in and out. Never full glow - like a dimming light bulb but not consistent - erratic. Got out - it beeped at me - pressed the lock on the key fob - nothing. Opened the door - no chime. Got in and it started right up - no check engine lights.

Drove to grocery store - turned off - light went glowing again - no door chime - but this time it locked when I pressed the key fob on exit. Came back - nothing. Wouldn't unlock. Pulled the cheat key from the fob, got in, and started up. No lights. Thought hey maybe its the fob - tried the other..same result. Glowing barely noticeable check engine for about 5 minutes after its shut off - then the door starts to chime. But now the fobs not locking or unlocking. When I walk away it beeps three times and inside its flashing the missing key symbol.

Pulled to see a code and only P0504. Why would it only dimly glow for a bit with the engine off - but clear as a bell and runs fine when on...

Go....

Edit - And I just went out with no key near it - and after an hour - the check engine iight is still half on.

Battery? Evap?

Maybe something got wet during the wash?

Don’t think so. Didn’t open the hood and I drove it for an hour after. As a note I did go out a few minutes ago. The light was off and the fob worked again.

Did u get gas while u were out? no idea what the code means but try ur gas cap maybe loose or off. Wife does this alot!!

Has it self-resolved then, you think?

Oddly this morning it’s fine. I did remove the pedal commander while it was going on but it lit the same light for a few hours after it was removed so not sure if related or not. Although I suspect anything I plug in can screw something up. I’ll keep an eye on it.

No but in Oregon we’re not allowed to pump our own gas so any other time that’s a possibility for sure.