R&R O2 sensors at once?

[cruxarche]

I got CEL code 21 on my 93: O2 sensor #1

I unplugged it and checked resistance per FSM. It did not register a reading on my voltmeter. I unplugged #2 as a reference and it was within spec. (well close, it read 4.8 and FSM says 5-6.5)

PO replaced both O2 sensors (NTK) within last year. Before I go replacing things I am wondering if there is a "root" cause that could have killed the sensor? Is there something else I should be checking before i just go and replace it. And, should I do both at the same time even though #2 is function within spec?

Thanks for your thoughts.

 

[CJF]

I'd do both, and with OEM Denso only. About the only way to guarantee you'll never have to worry about them again.

 

[bsmart82]

Have a dealer run your vin to see if the O2 sensor recall was done. If it has been done, I would use the oem recall kit since it comes with both sensors and gaskets.

 

[OGBeno]

Have a dealer run your vin to see if the O2 sensor recall was done. If it has been done, I would use the oem recall kit since it comes with both sensors and gaskets.

And the 4 nuts.

 

[cruxarche]

And the 4 nuts.

Beno, incoming pm.

 

[Timpanogos Slim]

The 93/94 o2 sensors are different than the rest, come in a pack of 2 w/ everything needed (except for high-temp copper anti-seize), and it costs $200+

My condolences on the expense.