Bad Rear O2 effect on gas millage

f550maranello2 · 10-23-2008, 06:08 PM

Ok so ever since i did the 5 speed swap iv had a code for the rear o2... i noticed that its dented on the side.. anywho.. how does that sensor effect gas millage cuz i its been pretty terrible lately...

i have not replaced it yet im thinking of putting a simulator in..

B_Eaze · 10-23-2008, 06:14 PM

pretty sure it has no effect on mpg . u should b good with a simulator

**Kevlo911** · 10-23-2008, 06:33 PM

According to the FSM it has no bearing on the way teh ecu controls the AFR.

My MPG after the 5speed swap sucks as well in the city(highway is fine, and I too have the rear o2 light)

*pmohr* · 10-23-2008, 06:44 PM

As has been said, the rear oxygen sensor does nothing but determine catalyst efficiency.

And in some cases, not even that... (95 fed spec ECUs, at the very least).

f550maranello2 · 10-23-2008, 07:14 PM

ok... so what about the ecu going into "limp mode" when the CEL is on?

*pmohr* · 10-23-2008, 07:20 PM

Quote:

Originally Posted by f550maranello2

ok... so what about the ecu going into "limp mode" when the CEL is on?

What about the supposed 'limp mode'?

f550maranello2 · 10-23-2008, 07:23 PM

sorry open loop

96blkonblkse · 10-23-2008, 07:27 PM

Ill be honest with you. In simple terms, the rear o2 makes sure the Cat is working efficiently/correctly as previously stated in most situations.

Now people "Say" it has no effect on gas mileage, i dont know, but honestly, i didnt have one for the longest time (96 catback on 98), i finally put it in to go thru aircare, and i noticed a increase in gas mileage. In no way was i driving the car easier, i dont know. Its one of those things, is the CEL worth 100$ or whatever it is for the sensor?