Cadillac converter

I have a 2002 Subaru Outback I have replaced a Cadillac converter and went to go get it smogged and it’s still saying the catalytic converter is not ready I have drove it about 3000 miles between 55 and 60 and it’s still not engaging what do I do

no matter what you do, your Subaru isn’t going to convert into a Cadillac. Good luck though.

Beyond that: what is the code you are getting? a 3000 miles drive should include whatever is necessary for a Subaru Drive Cycle, but without knowing exactly what code you have (or did have,) we are kinda left in the dark here. The code will likely be in the form of P0123


No codes. It just says cat not ready

What says “Cat not ready”?

Why did you replace the cat? because something said “Cat not ready”?


In OBDII, some systems are continuously monitored while others are just checked periodically during a drive cycle. The periodic tests are done when certain conditions during the drive cycle are met. There are about 9 of these I believe, but not all vehicles do all of them for what ever reason.

When you check for codes, there is an icon for each of the tests and it will darken or be crossed out or dim depending on whether the test has been completed, not completed or not required. You can have a test not complete but no codes.

It’s hard to imagine that you could go 3000 miles and not meet all the conditions required, but the cat test is one of the most difficult to meet. IIRC you have to drive for a certain time at a stead speed within a certain range and the engine fully warm. If all your driving is stop and go, you may need to get out on the highway and do about 55 for 20 minutes or so.

So i drove in on highway about 300 miles round trip for the last ten days.

When the cat was changed, the mechanic may have not completely sealed the exhaust system and there is an air leak. The other thing could be if the cat was changed because you had a check engine light with a P0420 code, the rear O2 sensor should have been changed instead of the cat and sometimes both O2 sensors have to be changed.

Both o2 sensor replaced but i will take it Subaru tomorrow after work to get whatever codes off code reader

I should have been clearer, you actually have two front O2 sensors and either one or two rear O2 sensors. You may also have up to three catalytic converters. You may have warm up cats, one off each exhaust manifold with the O2 sensor just in front. The rear O2 sensors may be just behind the warm up cats, aka pre-cat, hence two of them or just one sensor located behind the main cat. The rear are most often the main culprit.

See if you can get them to provide the drive cycle required to set the readiness monitor for the catalytic converter circuit. It could require more than just constant highway speeds. My Toyota required something like 3 minutes between 45 and 55 mph followed immediately by 5+ continuous minutes between 35 and 45 mph. If your Subaru is similar, it can be very difficult to accomplish.

I suggest you get your car re-scanned and see if there are any pending codes. It’s possible that replacing the cat was not necessary, but you have faulty O2 sensors.

And that is a good thing!


Assuming the replacement cat is compatible with your Subaru driving 3000 miles of varied driving conditions should be plenty enough to complete the computer’s readiness monitor. What might be happening is the computer is resetting itself and you don’t realize it. If the computer resets the readiness monitor has to start all over again. That could happen say if the battery was weak. Every time you crank the engine the voltage would drop so low the computer got reset. So check your battery and battery connections. Some scan tools are able to tell if the computer got reset recently.

Ok will do thank you

Will get them checked thank you

Ok thank you i will get them checked

The code reader that Subaru dealership hooks up to the car. I replaced cat because they told me the one under the front passenger was bad