Air Flow Sensor Switch
 

I think I understand that is a safety device that shuts off the fuel pump if the engine is not running. Owned my car for about 6 months and just discovered mine has been unplugged all this time. Plugged it back in and car runs exactly the same.

My question is, if the switch is working, as mine apparently is, why would anyone leave it unplugged? Does it improve driveability or idle or what? Should I leave it unplugged?

Thanks

Some people disconnect it to keep the pump running during diagnostics.
If it’ s working plugged in, leave it like that.

So your fuel pump doesn't run now when you turn the key to On (the position before Start), right? And it did before?

That's how plugging/unplugging it should work.

It does no harm to leave it unplugged - until you're upside down in a smoking wreck with it pumping fuel into the flames.

There's no advantage to leaving it unplugged - unless the switch fails or is mal-adjusted so that it doesn't work properly. Or maybe if your fuel accumulator or check valve doesn't keep pressure up in the system, it might start harder without the pump running with the key on.

They're usually just overlooked though, IME.

I had read a few threads here from the experienced guys that these are commonly found unplugged as mine was. Just wondering if there was any reason for it.

Thanks for your replies

The only reason could be for diagnosis as timmy2 said, where people forgot to plug it again afterwards or that it was simply forgotten when reinstalling the engine.

Anyway, it should be connected/plugged as its construction follows a secure aspect and prevents the pump running and therefore running/leaking gasoline i.E. after an accident.
And it prevents from running current trough the WUR and AAR if key is just turned but engine not started. This could cause wrong air/fuel enrichment behaviors when after some sec. key will be turned further for finally starting.