RedfishBluegrass

I just want to start by saying thanks for all the information on this site. It is incredible what you can find when you search. I am a very new 95 4runner owner after recently selling my 4th FJ60! So far I have replaced the coils in the rear, put my 32 BFG ATs on the stock rims (a little tight), Yakima Racks, Clarion stereo with amp, and hella reverse lights on. I will post some pics today. Now, on to the fun. My CEL came on so I jumped the diagnostic box and came up with a 27 code. It says its a HSO2 rear circuit. Is this just the rear oxygen sensor, I believe it has 2, and do I need to replace it. I have noticed the MPG went way down. Thanks in advance and I am glad to be a part of the 3slow crowd.

ZUK

iTrader: (1)

There are other things that will cause codes like that....bad spark plugs could cause an O2 sensor issue. How do the plugs look? You might think about a tune-up. Maybe the code will go away then.