So i have had a sudden drop in MPG i use to have a misfire but the code cleared itself seems odd to me. i have bank 1 sensor 2 no activity on my o2 sensor. Can this affect MPG greatly? The O2 sensor is currently covered in oil from an oil leak that i can't seem to find and its all over the connector also could the 02 be fine and it just be the connector and if i replace the O2 will it just die again because of the oil leak?

 

change you upstream O2 sensors clean the area really well before you replace and use the Dielectric grease on the connections, this will help in protecting the connectors from grease, dirt and water. Also how old are your plugs and wires

 

Can this affect MPG greatly? YES

 

Wires haven't been replaced since i own it records show they were replaced at 100k i replaced the plugs at 126k miles with NGKs

Do i need to replace both sensors at the same time

 

You are absolutely crazy to run around with bad O2 sensors.
You want to ruin your cat converters?

You are my friend ON THE WAY to doing this.

ALL the gas that is dropping the MPG is going into the cat converters and superheating them.

Please STOP driving it and fixing it.
You are also polluting the environment more.

Sorry to be harsh - but this is true.

 

Oh wow i had no idea i was wondering why there was a heat buildup in my floor board!

 

can i replace just one or do they need to be replaced in pairs

 

replace all 4 you can get them on amazon for around $50.00

 

I can't wait on shipping so I'm having to buy them local being its my only car i have during the day and i have to use it to get to work. can i save money now and only get the front 2

 

yes do them in pairs.. ups then downs. best to do all 4, but anything is better than notta......