O2 sensors

New to forum. I have 2 questions: I need to replace the O2 sensors on my recently acquire 01 runner. I am finding conflicting info. - are there 2 sensors or 3 and is it best to use DENSO?
2nd- the keyless entry fobs aren’t working. I replaced batteries, replaced fobs and reprogrammed- still no luck: is there a receiver or something inside the vehicle to replace?
Thank you

 

Welcome. I posted the manual to the alarm in a post below. It may help with pairing up the remotes.

 

Seems my pdf isn’t loading. To pair the new remote to your alarm....

 

There are 2 O2 sensors. Do yourself a favor and get Denso only.

 

yes , exactly...i replaced both of mine...and the check light & codes, stopped.

 

Remember...some 4Runners came with downstream A/F sensors and not O2 sensors. Make sure you know which is which. They look the same.

 

How do I know? I need to change mine soon and was gonna buy the upstream and down stream ca compliant O2 sensors now I'm hesitant because of A/F sensor?

 

1999-2000 had 02 sensors.

2001\2002 could have either.

Call your dealer with your vin. They can tell you the exact part number and you should be able to cross reference it to what kind it is.