Hi there! I bought my own OBD II reader and these were the three codes that showed up. P0031, P0442, P2097. My main question is if they're related and if I need to worry about fixing anything soon.

 

Further analysis: The P0442 code is not a gas cap problem, so I'm assuming it's a small leak, but I have yet to smell any gas while running my car. The P0031 code, O2 sensor fail, does this mean it's just the sensor that failed or that there's an O2 problem? The P2097 code says that my fuel is too rich or there's a faulty O2 sensor... could it just be that my O2 sensor is broken because of the P0031 code I read? I have yet to notice any rough idling, misfires, bad fuel economy, or anything that would show there's a problem with my car.

 

Any help would be greatly appreciated! Thanks, Jenna

I'd clear the codes and see what comes back.

Oh I'm sorry. I cleared the codes a few times now and these are codes I'm getting consistently. Thanks

02 sensor is most likely the reason why the car is running rich. P0442 is showing up because there is an evap leak somewhere, could be showing up because evap canister/hose leaking. Even an incorrect fuel cap can set this off. The 02 sensor failed, its an easy fix but usually they are on there pretty good due to constantly being heated and cooled.

I agree with it needing the oxygen sensor. The P2097 is a post catalyst fuel trim too rich but that doesn't mean it's the rear oxygen sensor issue. I would start with replacing the front air/fuel sensor (front oxygen sensor) first, clear the memory and see what comes back. I also know that there was a dealer campaign on some Subarus of that era that needed an ECU reflash for the P2097 as well but it's always good to start with the air/fuel sensor.

Thanks everyone! Is that a repair I can do, changing the fuel sensor? Or is that something I should take to the dealer?

You just unthread it from the exhaust and thread the new on in.

 

But they are generally very tight to remove due to heat cycling, rust, etc.

Did the front O2 Sensor take care of your P2097?

Have it on the wife's 2006 Forester.

Thanks,

Larry