I got a check engine light yesterday and checked the code (27). The book says O2 Sensor Malfunction, replace O2 sensor.

I called Toyota, and they want $140 for a new sensor!! Wow, I guess I thought small part = small price.

Anyway, before I drop $140, is there anything else I should check first? Wires? Fuses? Are aftermarket O2 sensors any good?

Oh yeah, I checked my code with the following link:
http://www.off-road.com/toyota/tech/codes/

Another Oh yeah, there is an O2 sensor before and after the CAT. Which one to replace? Both? Hope not.

Thanks,

Rich

1993 4X4 Toyota Pickup XtraCab
22re (ATK Remanufactured)