[Volch_de_la_ubaru]

Hello, I am new to this style of forums, but I am determined that others are the best way to resolve my problems with my new Subaru.
Here is the backstory: Bought a 2005 Subaru legacy Limited 2.5gt wagon Tuesday, 11/12/19, I test drove it, felt smooth, fast, very clean car no lights or issues. Not knowing the last time oil or maintenance was done on the vehicle, I took it to my local imports shop, who specializes in foreign model cars. I had them do medium service described by them as:

• Adjust Idle Mixture
• Inspect & Adjust Drive Belts
• Replace Engine Oil & Filter
• Inspect Air Cleaner Element
• Inspect Throttle Body
• Inspect & Adjust Timing
• Inspect Ignition Wires
• Adjust Rear Brakes
• Adjust Parking Brake
• Inspect Front Brake Pads
• Inspect Rear Brake Pads
• Inspect & Adjust Clutch Free Play
• Inspect Exhaust System
• Inspect Power Steering System
• Inspect Suspension System
• Inspect & Adjust Tire Pressure
• Change Transmission Fluid
• Rotate & Balance Tires
• Lubricate Door Hinges, Locks & Latches
• Road Test

So whatever, awesome, they made notes about possible timing belt change, and some other things that I would have to pay more to fix, change.
So drive home, no problem. Untillllll the next day Saturday morning 11/16/19 I am driving 35 miles to a farm I work on. Country roads, I planned on testing speed, enjoying the drive. I'm going 60ish and finally figure out how to turn on cruise control. Flick it on, then off just to test it. few minutes later.....
BAMMMMM
CEL light is glowing like a christmas tree, and that cruise light is flashing. A depressing 80 miles into owning this vehicle. I do some research and it seems it can be a light fix or a big expensive lemon.
I take the car in and get it scanned by an Auto Zone OD2, and it says Cat needs replaced because of a P0420, Well heck me right? So I do some more research and find out maybe it is an 02 sensor, before or after the Cat, or maybe a Vacuum leak, or something.
So here is the facts:
05 Legacy 2.5turbo, 150,000 Miles, I have drove it for a total of 150 miles, Filled the gas tank up once with premium fuel.
CEL light on, and blinking cruise light,
CHUGGGING through gas like no tomorrow,
awful MPG,
and after having the air on for awhile I get a not so pleasant smell from the vents.

What do yall recommend? Should I go back to the shop and ask if they messed with something? Is this a by chance accident? Should I contact the dealer and see what they can do/say? It was a small dad and son cash only place in town. Do yall think this is something I can fix myself? Is this a lemon?

 

[Subie_Gal]

Go back to where you bought it. Tell them that the code just showed up. The cat converter might not be stock (aftermarket cat converters are notorious for not working). Also, that CEL might have come on earlier and could have been cleared by the seller. Replacing a battery clears codes, too. It takes ~100 or so miles for the main computer to re-read all sensors, so if the seller cleared the P0420 you would not have noticed any problem driving it, nor would any mechanic notice a problem with the routine maintenance done. The CEL would show up after you'd driven it a while.
The flashing CRUISE light happens usually when the CEL comes on; the system is shutting down your cruise control as a precaution until the problem is fixed.
The smell may be your cabin air filter and/or engine air filter. They probably haven't been changed in a long time and are full of crud.
Chugging through gas: If you have a problem with your exhaust or catalytic converter, it could show the upstream symptom of lower gas mpg.
I'd have this car inspected by a very, very thorough and honest mechanic. An O2 sensor isn't terribly expensive to fix. Air filters are cheap to fix. Cat converters (Subaru oem) unfortunately are not cheap and aftermarket cats are notorious for not working right. The cat converter replacement may be more $$$ than you paid for the car.
If it turns out that the cat converter is bad, then take that information and all the problems back to the seller. There may be a "lemon law" in your state. Good luck and hope you can resolve it.
Addition: Here is a link to another thread here, with good information about this kind of problem. https://www.subaruoutback.org/threads/p0420-diagnosis.49537/

 

[RoughDiamond]

First, I'd not call it a "lemon". That term actually has a specific meaning and doesn't apply here (or especially to used cars). You may have a got a rescue that was beaten and abused, but not a "lemon".

Secondly, I'd ask the shop what exactly they did as half the items on the list you posted are not possible on this car(i.e. adjust the idle mixture, inspect plug wires, adjust the rear brakes, etc).

As you have found, it could be something else causing this code. However, in my experience, it's likely a failed up pipe converter. My money is also on the turbo being a newer unit, possibly a cheap, Chinese knock-off that could have also failed (again). These small "buy-here, die-here" places do not have the budget to buy good, replacement turbos.

Have another, more Subaru-inclined shop evaluate.