1999 Toyota Tacoma oxygen sensors, HOW MANY?

[quote:9150c9e763="gpman"]Engine Performance problem
1999 Toyota Tacoma 6 cyl Two Wheel Drive Automatic 133000 miles

I want to replace the oxygen sensors that are on the PRE CATALYTIC side of the exhaust. How many PRE CAT sensors are there? I'm confused because I only see one just before the CAT CONV but some info that I have, if I'm reading it correctly, says there ARE 2 pre cat sensors, Bank 1 sensor 1 and Bank 1 sensor 2, and 2 post cat sensors. (I only see one post cat sensor just after the CAT CONV) If there are 2 PRE CAT sensors where is the other one located?[/quote:9150c9e763]

Hello,

Here is how the Banking on o2 sensors go....

Bank 1 Sensor 1 would be Passenger Side in the Exaust Manifold

Bank 1 Sensor 2 would be the next sensor back or in just before the Cat.

Bank 2 Sensor 1 Would be Driver Side in Exaust Manifold.

Bank 2 Sensor 2 would be next sensor back or infront of cat.( this would be on a dual exaust system)

On some vehicles there are 2 pipe that will go into the engine side of the cat and there will be an o2 sensor in each at the cat.

Any other would be after cat.

Hope this helped.

We Appreciate the Donation...

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