Which is the bank 1 # 1 o2 sensor on a 2004 rav 4 4cyln

SOURCE: O2 sensor wiring diagram for 2004 hyundai sonata

there is two wires then suposed to be same color they are not what you looking for but if you have a grey and a black wires it willl be one of those i hope and this help

SOURCE: more 99 cougar problems

there is a fuse for the o2 heaters if one of the sensors blew the fuse they will all be out

SOURCE: location of bank 1 sensor 1 o2 sensor

Should be in the manifold on the back side closest to the firewall.

SOURCE: 2004 Sequoia. VSC TRAC, TRAC OFF, and Check

It is not hard to change the sensor, it just screws into a threaded hole. The light will not go out immeditaly, after the sensor is replaced. It needs to go thru a drive cycle. Your best bet is to replace the sensor and get the code cleard by whoever scanned it for the 0031 code.

SOURCE: have p0130 and p0133 codes 98 toyota tacoma

I would check the O2 sensor, and if it checks bad, replace it, and clear the trouble codes. If the light comes back on, you may need to check further. .