Bad mileage due to defective o2 sensor?

[Paramedic]

Can a defective o2 sensor affect the mileage?

With a full tank of gaz I'll do about 450 km highway (2H) and about 300 km if not less in the city (2H).

When im in 4H it's a little bit worst (I live in Quebec, Canada so we always have 20 cm snow storm like today!!!!! FML).

Pat

 

[jgue467]

What MY? Yes - Especially if its functioning as an air/fuel ratio meter like the front one does on cali models. :cowboy:

 

[gamefreakgc]

Absolutely. The front O2 sensor controls your fuel trims, if it's gone rouge on you and is sending bad readings it will affect your mileage.

 

[Paramedic]

I have the P0141 error.
I think it's the 2nd sensor ?

 

[gamefreakgc]

Oh by the way, you don't need to start a new thread if it's relating to the same issue. You could have posted this question in your other thread and we could have answered it there. No harm done though.

 

[JayRolla]

I believe the P0141 is the rear o2 heater sensor is bad. The o2 sensor has a heater that warms the sensor and keeps the car in open loop until its warm enough to switch over. The rear o2 sensor doesnt actually do any of the adjustments for air/fuel like the front but when the rear goes out it tells the ecu to go into open loop which will kill gas mileage.

 

[MONTYMTB]

I believe the P0141 is the rear o2 heater sensor is bad. The o2 sensor has a heater that warms the sensor and keeps the car in open loop until its warm enough to switch over. The rear o2 sensor doesnt actually do any of the adjustments for air/fuel like the front but when the rear goes out it tells the ecu to go into open loop which will kill gas mileage.

I recently bought an Ultraguage, and the reading on the rear sensor is always all zeros. No codes - pending or current - and it will always go into closed loop. Last tank I averaged 18 mpg with 90% highway miles. I've thought about replacing it, but from everything I've read on it I can't decide if it's worth the $50 to do it.

 

[JayRolla]

I recently bought an Ultraguage, and the reading on the rear sensor is always all zeros. No codes - pending or current - and it will always go into closed loop. Last tank I averaged 18 mpg with 90% highway miles. I've thought about replacing it, but from everything I've read on it I can't decide if it's worth the $50 to do it.

yes ive heard this also. You can make a circuit to bypass it. If ecu goes into closed than your golden.