Me and my friends were wondering how badly does bad 02 sensors effect gas mileage? Does anyone have the slightest clue? I was thinking somewhere in the ball park of 1 mile per gallon difference? Just curious, thanks in advanced

 

i have 2- o2 sensor going bad and didn't lose any MPG.

 

It depends on what goes bad. A heater can go bad and not affect mileage by much. If the actual oxygen sensor part of the sensor goes bad, then it can really affect mileage.

 

Yah both of the 02 sensors went bad. It seems something is hurting my friends gas mielage a lot and we are thinking thats it. There is also a rattling coming from the muffle. No leaks or anything anywhere so i'm thinking it clogged up and got stuff up in there. Does the muffler be clogged effect mileage and performance a lot?

 

If the muffler is clogged, it is from the material inside the catalytic converter that has burned out, broken up, and blown into the muffler. The cat would have to be replaced first, then the muffler or preferably, both at once. Have you noticed any performance issues? How many miles on the truck?

 

theres 140k on the truck. I think there could be mud in there maybe because it was sunk once before and water and mud was shooting out of the exhaust pipe when we started it back up after draining the engine from water. its been getting worse mpg. And when you give it gas and let off, the rpm needle seems to go down a little slower. I could be wrong on the rpm needle but i wasnt sure. we plan on putting a new cat and exhaust on anyways