I found some information about the code P0158, but I’m not sure where the “bank 2 sensor 2” is. I know it means the second sensor on the car, but I’d like to know exactly where it is. My boyfriend just noticed his check engine light has been on for a month.
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The sensor on the passenger side, after the catalytic converter, is the one we’re talking about. There are four sensors in total—two on each side, one before and one after each catalytic converter. The one after the converter shouldn’t affect your fuel economy. You can try resetting the code to see if it comes back.
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I asked my boyfriend to get the code cleared at the shop, but I wasn’t there to see if he actually did it. Is there a way to reset the codes myself? I bet I could find out if I looked it up. 
Also, since it’s the sensor on the passenger side after the catalytic converter, does this Jeep have a header catalytic converter, or just the regular one before the muffler?
Thanks again!
I disagree that it hurts fuel mileage. In my Jeep, the same issue happened, and I used up half a tank of gas in just 60 miles on a road trip. I stopped at a gas station, disconnected the battery to reset the code, and refueled. The next time, I got 200 miles on just half a tank, and the warning light was off. That’s crazy!
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The original post was about an “after the cat” O2 sensor, and that’s what I was responding to. This type of sensor only measures exhaust gas temperature and shouldn’t affect gas mileage.
But if it was one of the “before the cat” sensors, it would impact how the engine runs in cold conditions and could change your gas mileage.
So, what was your error code, and which O2 sensor was causing the problem?
How many O2 sensors does the 2004 Jeep Liberty have? My check engine light is on, and the code is P0158. I’ve already changed three O2 sensors, but the light is still on. I disconnected the battery, but the light came back on. I took it back for another check, and the P0158 code came up again, saying it’s an O2 sensor issue for bank 2. Can someone help me?
You don’t need a code scanner to check for codes. Just turn the ignition key on and off three times without starting the engine. On the third turn to the “on” position, leave the key there. Any “pending” codes will show up on the odometer display.
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Does not work on all years and only displays generic “P” codes.