Check Engine light in 96 Outback with 2.5L

[csterlin]

I just bought a 96 Outback yesterday. It is an automatic with the 2.5L engine and has 148k miles on it. Today the check engine light came on. Yesterday when I filled it up for the first time, I did not see the sticker recommending premium gas until after I started filling it with regular. Could the regular gas have caused the light to come on? If not what might be the cause? Also, if it is the gas, will I be able to reset the light after I fill it with premium? And finally, if the gas is the cause, are there adjustments I can make to get it to accept regular without setting the light off?

Thanks!

[AWDFTW]

If you are in the US (you don't say), any auto parts store will read the code for free. Without knowing the code, we can't do anything but guess. Get the code read and post it here.

Our old 96 got regular when my wife filled it up and premium when I did. The knock sensor should be able to handle this if it is working correctly. I found the car to run smoother with premium, but the power and MPG were the same regardless of the octane in the tank. So I do recommend premium, just because it was designed to run on that fuel.

[csterlin]

Thanks for responding. Yes I am in the U.S. I took it to Advance and got the code. It is P0420 Catalyst System Efficiency Below Threshold Bank 1. So it looks like it's the catalytic converter. They cleared the code for me so I'll see if it comes back up and if it does, go from there.

[4wheeldog]

There are a bunch of things it could be other than the cat itself......And most of them are cheaper. First, check to see if it is a Subaru cat. Folks report a lot of problems using aftermarket cats. If it is OEM, then your MAF sensor and O2 sensor would be suspect, before the cat itself.

[RobLog]

There are a bunch of things it could be other than the cat itself

Yep, that's right. To the OP: If the code comes back, search the forum for P0420 ... there are several good threads on fixing this issue.