O2 sensors killing my gas mileage?

[lemonhead401]

I have a 1990 LS400 and my check engine light has been on since I have owned the car. I assumed it was the O2 sensors or cat seeing as the car runs fine. The problem is I am getting around 14 mpgs, the worst I have ever gotten. Is it possible that the O2 sensors are bad and causing the car to run rich and would getting 4 new ones drastically change the mpgs. I have had 2 other LS400s and they all got in the low 20;s city and upper 20's on the highway. I am getting a new air filter too.

 

[do92sc400]

I have a 1990 LS400 and my check engine light has been on since I have owned the car. I assumed it was the O2 sensors or cat seeing as the car runs fine. The problem is I am getting around 14 mpgs, the worst I have ever gotten. Is it possible that the O2 sensors are bad and causing the car to run rich and would getting 4 new ones drastically change the mpgs. I have had 2 other LS400s and they all got in the low 20;s city and upper 20's on the highway. I am getting a new air filter too.

It is not wise to guess what could be wrong when you have a check engine light . Best thing to do ischeck what the computer is telling you. Malfunctioning o2 sensors could cause bad mileage, but there could be other variables, such as basic tune up, ignitio system not working properly ect. Check the computer first.

 

[Nick M]

What he said, it is spot on correct.