2020 SE manual: mechanical/electrical noise when car is off

#1
Ok, this one is really weird. Both my wife and I noticed on two separate occasions recently that there's a mechanical/electrical type of noise coming from under the car hours after the car was shut off. It sounded vaguely like a fan running -- a humming, gently vibrating sound, almost like the radiator fan. To me it was most noticeable toward the rear of the car, which made me wonder if the electronic e-brake was trying to engage. I actually got down and put my head under the rear of the car to see if I could better isolate the source, but when I stood up to move to a different position the noise stopped. I estimate it was going on for at least a minute or two while I was investigating, and I don't know how long it was on before I noticed it.

I'll try to see if it occurs again. If so...and before I bring it to the dealer...can anyone think of any possible reason why something would be running hours after the car is shut off? I'm a little concerned that something is malfunctioning, and that it's going to kill the battery sooner rather than later. The only other thing I can think of is the anti-theft/alarm system. I didn't have my key with me, so I don't think it would be anything to do with the proximity sensor for unlocking the doors.
 

jolly

New Member
#2
Perfectly normal. From your owner manual p. 6
"Approximately five hours after the engine is turned off, you may hear sound coming from under the vehicle for several minutes. This is the sound of a fuel evaporation leakage check and, it does not indicate a malfunction."
 
#3
Perfectly normal. From your owner manual p. 6
"Approximately five hours after the engine is turned off, you may hear sound coming from under the vehicle for several minutes. This is the sound of a fuel evaporation leakage check and, it does not indicate a malfunction."
Awesome, thanks @jolly! Earlier I was thinking, "maybe I should see if there's anything about this in the owner's manual" -- but I didn't get around to it. And I thought it was a long shot anyway.

Out of curiosity, was this something that you had previously noticed in your car and/or just happened to come across when browsing the manual? To the best of my knowledge I've never had a car that ran a diagnostic test like this, many hours after the car was shut off. I learned something new today. :)
 
#5
A bit of both as this has been on many cars for many years but I'm also in the bizarre minority that do read instruction manual o_O (I mean when I get the car, not just when something happen).
Wow, I guess things have changed since the last time we bought a new car before this Corolla (15 years ago)! I'm not yet used to newer tech it seems.

I don't think it's weird to read the owner's manual. I actually spent a bit of time with the Corolla's manual to get familiar with some features of the car. However, I didn't read it starting from the beginning like it's a book. I started by looking at the maintenance schedule, then read several sections that were of particular interest and helped me get familiar with some aspects of the car I was curious about. I soon determined that the manual is _not_ very well written, and in fact I found it more irritating than useful. But I acknowledge that the manual would have set my mind at ease WRT this weird-to-me noise if I had bothered to read through page 6! :D
 

jolly

New Member
#6
I guess things have changed since the last time we bought a new car before this Corolla (15 years ago)!
Actually, it has been in cars for more than 15 years (since OBDII - 1996) but might have got unnoticed since the procedure may vary according to manufacturer and in all cases it only occurs when certain conditions are met (fuel level, outside temp, mileage since last check, etc.).
I soon determined that the manual is _not_ very well written
I couldn't agree more !
 
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