I haven't found any threads on how to replace oxygen sensors, could anyone please help out, it's a 2004 AT rx8

 

WBO2 is on exhaust manifold.....plug is up behind the oil filter..bit of a PIA to get at

Rear Narrow band is on the midpipe..plug is up above it on the tranny...

Unscrew....reinstall new ones....done

 

Still don't understand but how soon do the O2 sensors have to be changed , I got 98000 miles just had d plugs n coils changed , plus I think one of the speed sensors in my back tires are damaged I can't go past 80 without the brake light, abs light and traction control light coming on , any suggestions will be welcome gratefully

 

The ECU should throw a CEL when they quit working......

As for the speed sensor....did something happen? Usually they are damaged by pulling on them or such. If you know it is damaged..then replace it..

 

I have a 2004 Mazda RX8, apparently my CEL is on and the Mazda dealership told me its the rear O2 sensor. When I replace the sensor, will the CEL go out after disconnecting the battery or is there something I must do?

 

Re-set the ECU by disconecting the battery for 10 min.

 

the ecu will identify a bad o2 sensor once it reachs certain parameters--i too have been wondering if it would aventacious to replace the front sensor but then i data log and all is well.
olddragger

 

There are two part numbers for these it seems. Anybody know the difference?

N3H3-18-861B-9U
N3H2-18-861C-9U

 

N3H3 is for Manual Tranny

N3H2 is for Auto.

Both are Rear O2.

Front O2 is

N3H2-18-8G1B - Auto

N3H3-18-8G1A - Manual

 

Thanks

 

What's th -9u at the end? I got N3H3-18-861B from mazda for mine, but the parts im looking up have a tagged on 9U

 

The -9u is a north America only thing, it just means the part is locally sourced and put into a pretty Mazda box.