I recently bought a 2008 Subaru Outback 2.5i, 4-Speed Automatic with 220k miles on it. Overall, I'd say the car runs fine and reasonably smooth, but is slow to accelerate when in Drive and won't go faster than 60mph even with the pedal to the floor. In this scenario, the RPMs will hover around 5k+ and the engine temp rises if I try to keep pushing it. It simply won't shift/gear up on it's own at that speed in order to continue accelerating, at least in the default Drive mode.

This seemed like a huge issue, but I put the car into Sport and used the third gear to get up to highway speed (70-80mph) easily and fourth gear to stay there when the RPMs got high in third. I haven't tried to push it further/faster since there is no need or opportunity to try driving faster. The engine temperature stays normal when highway driving in Sport and shifting gears/speeds myself. The RPMs hover around 2-3k I believe when cruising in fourth. Gas usage/MPG seems normal. The vehicle passed emissions in Colorado yesterday.

I don't know anything about cars and this Subaru is the one on which I want to learn. I don't have the money to do so yet, but I want to work on this machine and hopefully get another 200k+ miles out of it. I hope to know it in-and-out after a couple of years and be able to do most basic maintenance myself or at least be able to diagnose problems myself (with research) and determine what I can do myself and what I can not.

I don't have any computer error codes to reference at this time. The check engine light does not light up, nor do any other warning lights I am aware of. Would the car still throw codes if I took a computer reading of it despite no other warning signs? Could this be a transmission issue even though it seems to work fine in Sport mode? I've also read it could be either an air intake/filter issue or an exhaust issue. Honestly, it seems like it could be a handful of different things.

Thanks in advance for any insight and help!

EDIT: The issue was that both catalytic converters needed to be replaced. The front was melted inside and the rear was clogged. I'm in Colorado so I needed CARB rated replacements, which are quite expensive, but not as expensive as OEM replacements in the area. I spent $3200 having my local garage fix it, which sucks, but it drives like a dream now. Hopefully the next person who finds this thread finds this helpful. If you don't live in California, Colorado, New York, or Massachusetts, you can buy much cheaper converters (at your own risk). Installation/labor was a fraction of the converters themselves. Based on an inspection of my car, nothing else was wrong. For disclosure, I'd had a solenoid replaced prior to this issue starting, but that didn't change anything. Cold weather made it much worse.

  • Is this a turbocharged engine? Oct 14, 2022 at 15:36
  • Check for the type of automatic xmission. A search reveals all 2.5L engines use the continuously variable transmission (CVT) that are unique compared to traditional automatics. Basically a cvt uses variable steel pulleys hydraulically controlled for infinite gear ratios using a steel segmented belt for durability. However, CVTs are known to fail and usually cannot be repaired. Replaced. Whether or not you're experiencing cvt issues requires either a trip to Subaru or an expert on Subaru CVTs. Other manufacturers use CVTs too with varying success along with problems.
    – F Dryer
    Oct 14, 2022 at 21:39
  • @Pᴀᴜʟsᴛᴇʀ2 When I lookup the VIN, I keep finding the engine described as such: "2.5L H4 SOHC 16V" I see no indication online or on the vehicle itself (branding on rear, model/trim variation, etc.) that indicates it's turbocharged. Is there a way I can verify that elsewhere? Pardon my ignorance here and thanks for reaching out!
    – trey
    Oct 15, 2022 at 20:36
  • @FDryer Thanks for your insight! I definitely plan to get a full inspection from the local Subaru dealership when I can.
    – trey
    Oct 15, 2022 at 20:38

1 Answer 1


This sounds similar to a common issue on these models with the catalytic converter substrate physically breaking down causing an airflow problem. I've seen a couple of cars with this issue and no check engine light.

Of course it could be plenty other things too. Anyway it is easy to unbolt the cat, give it a shake and see if anything is loose. Please let us know how you get on, or what the problem ended up being.

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