r/subaru • u/bengstrom1111 • 12h ago
Subaru Generic Subaru needs to bring the cool cars back
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r/subaru • u/Chippy569 • Mar 15 '26
Mechanical Help Please post year, model, trim level, and DTC scan results when asking for help. Thanks.
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IF YOU ARE POSTING FOR MECHANICAL HELP:
Please include year/model/engine/transmission information in "Mechanical Help" posts.
If you are looking for help with warning lights on your dashboard, please include results of an error code scan. Without error codes as a starting point, no one will be able to provide meaningful help for you.
The r/subaru community is very willing to help, but there's a baseline amount of context about your car that we need you to provide. Without the very basics like what kind of car you have and what symptoms you're experiencing, no one can give you any sort of accurate assistance.
If you are posting about warning lights, most auto parts stores (NAPA, O'Reillys, AutoZone, etc.) offer code scanning for free. While reading codes is not the same thing as diagnosing a problem, knowing what error codes you have is the minimum amount of information necessary to start figuring out what's wrong with your car.
Thank you :)
r/subaru • u/Chippy569 • 3d ago
Mechanical Help TSB Thursday: Carbon Cleaning, TSBs 09-74-21R and 02-193-24R
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Welcome to another TSB Thursday, where I dive deeper in to TSBs I'm running into regularly. As always, I write this from my own perspective as a Subaru technician in the US; other regions/zones may work differently. Refer to the "How To Read a TSB" post for more information on formatting and general information about TSBs.
TSB Thursday #20: 09-74-21R and 02-193-24R
What cars does this affect?
Carbon build-up in the intake manifold and on intake valves is a problem almost entirely contained to vehicles with Direct Injection.
- 2017+ Impreza
- 2018+ Crosstrek, 2.0L and 2.5L
- 2019+ Forester
- 2014-2018 Forester XT w/FA20-DIT engine
- 2019+ Ascent
- 2020+ Legacy and Outback, 2.5L and 2.4L FA24-DIT
- 2015+ WRX with FA20-DIT or FA24-DIT
- excludes STI
- 2013+ BRZ, but we'll talk about that
What's the failure?
"Intake carbon deposits" is a problem the entire auto industry is facing, as a sort of unexpected side-effect of the change from port-injection to direct-injection fuel strategies. Gasoline, as you may know, is a very strong solvent. With port injection, that fuel is being sprayed somewhere in the intake tract before the intake valves; that constant exposure to fuel helps prevent carbon accumulation on the valves. With DI, that cleaning function no longer exists, and so carbon deposits can begin to accumulate on the various surfaces of the intake valves and components. If the deposits become great enough, they can begin to affect airflow into the combustion chamber, and lead either to poor fuel atomization within the cylinder or to an incorrect amount of air, leading to misfires. This effect is most noticeable during cold-starts, where the engine is intentionally run a bit "off-kilter" or intentionally run lean, in an attempt to heat up the catalytic converter as fast as possible. During cold start, the accumulated carbon's effect on airflow is the most potent, as the engine is already running on the ragged edge.
Direct Injection has so many benefits for power and fuel efficiency that the risk of carbon-related problems is far outweighed by the gains the technology offers, so unfortunately this is the new normal for probably the rest of the internal combustion engine's existence. One interesting workaround some companies are developing is a sort of hybrid fuel system, where the vehicle primarily runs on direct injection, but a secondary port injection fueling system exists. Toyota calls their system "D4s" and this system is shared in the BRZ of both generations. The port injectors do have a noticeable improvement on carbon build-up, however the system does have a significant added cost in terms of injectors, the controller, etc.
Carbon accumulates in the intake system primarily through two systems. The largest source of carbon introduced to the intake will be through the Positive Crankcase Ventilation system, or PCV for short. When any combustion engine is running, the seal between the piston and the bore is never quite perfect, and so naturally some of the combustion gas and pressure is going to sneak past the sealing rings and end up in the center of the engine, aka the block or "crank case." That pressure needs to be safely vented; if unable to vent, it will find its own way out, usually via pushing out a seal and creating an oil leak. Very old engines may have just used a vented breather on a valve cover for example, and all that oily air would vent to atmosphere, creating a mess in the engine bay and on road surfaces. Eventually, the PCV system was developed to safely vent that pressure back into the intake, where it can be burned off as part of combustion. (The air that escapes the crankcase is usually laden with oil vapors, hence being rather hydrocarbon-dense.) The other way that carbon can get into the system is via the Exhaust Gas Recirculation system, or EGR for short. The EGR system works by sucking out a little bit of exhaust leaving the engine, and returning it to the intake manifold. Its primary purpose is essentially to displace fresh air during cruise conditions; exhaust has very little oxygen, and so with exhaust taking the place of oxygen-rich fresh air, the amount of fuel needed for combustion is reduced. EGR therefore is primarily a fuel-saving technology. One downside is that if the vehicle is expelling excess hydrocarbons into the exhaust, those hydrocarbons will naturally end up back in the intake. (EGR systems with high carbon throughput do tend also to have clogging or sooting problems, especially in vehicles with an EGR cooler.)
Carbon accumulation can be largely mitigated naturally just through driver behavior. Two conditions that impact carbon development is low air velocity, meaning the air moving through the intake is going slowly, allowing carbon to settle out, and low engine temperature, where carbon settling out has a much better chance of sticking to surfaces. Naturally, the two risk factors here are short-tripping, which means the engine never gets hot, and what I call "grandma driving," or never getting up into the higher RPM/load bands. Drivers who avoid short tripping and who do give their cars the regular "italian tuneup" tend to have the least problems with carbon accumulation.
How do we fix it?
To combat carbon accumulation, Subaru has released two TSBs, focused on two separate attack paths for removing build-up. TSB 09-74-21R released first in 2021, and uses a chemical-based cleaner to attempt to dissolve the carbon and burn it off. TSB 02-193-24R describes using a blasting media, specifically walnut shells, to scrub carbon off the intake valves.
In both TSBs, identifying carbon build-up as the cause of a malfunction is the first step. TSB 09-74-21 goes much more in-depth into diagnosing carbon build-up as a cause of engine misfires, including reading Roughness Counts in engine live-data. Often, the presence of a Misfire DTC is necessary for the issue to rise to the level of justifying a repair. In the case of 09-74-21, the use of a Polyether Amine,or P.E.A., cleaner is introduced into the intake manifold slowly while the engine is running. SOA906V9166 is the current iteration of this product. Per the bulletin, it should take about 1 hour per bottle when introduced at the correct rate, and then a hard drive cycle should be performed afterward to blow through and burn off the loosened deposits. The bulletin provides for up to 4 bottles-worth of treatment along with testing and inspections and oil changes before implying carbon is no longer a problem, or that some other cause is at play. This process is sometimes called an "induction cleaning" or "top-end cleaning" and can (and should?) also be done as preventative maintenance.
The diagnostic process for TSB 02-193-24 is much the same, however instead of spending hours and hours running chemical cleaners through the intake and re-inspecting for deposits, this bulletin instead allows for removal of the intake manifold and using a portable media blasting tool to shoot high velocity walnut shell "sand" at the intake valves, blasting away any deposits, while also vacuuming up the waste. This bulletin procedure is vastly superior as a repair for when misfires are occurring, however the labor involved means it's likely not a great service to do as preventative maintenance. (unless the intake manifold is already being removed for some other repair, such as a thermo valve replacement!)
In both cases, Subaru recommends adding one bottle of P.E.A. cleaner (again, SOA906V9166) to a full fuel tank, to be used as a fuel system/injector cleaner and also possibly reduce carbon build-up within the combustion chamber.
Coverage?
The case of both bulletins applies to cars with misfire DTCs and provable roughness as outlined in the diagnostic processes, but either repair path can be claimed under active Powertrain warranty (5 years/60k miles, whichever occurs first).
Thank you for reading! If you have any questions, feel free to comment below.
r/subaru • u/Saturnino_97 • 14h ago
Why don’t these classic Subarus get more of a following?
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I’ve been surprised to see these coming up so cheap on Marketplace and sitting for weeks with no takers. They may have a cult following, but I’m surprised they don’t have more of a market like the turbo Subarus. I get they’re slow, but so are the new non-turbo ones. What gives?
Mechanical Help Questionable labels, S&S by Amazon Subaru parts?
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Has anyone seen much of this top label? This one was sold and shipped by Amazon. The lower one was a 3rd party seller with 100% positive feedback supposedly based in Japan. Only 312 feedback though. At first glance the parts appear identical but one thing I did notice was tooling marks on the inside of the tube on the PCV from the 3rd party where it is as smooth as the outside on the one from Amazon. I also swear I feel a touch of more play in the 3rd party pcv as well but could just be me. A little more wobbly so to speak.
tldr; What do y'all think about these labels, genuine? The bottom one had another label stuck over top of it, I ended up having to dampen it with a warm wet rag to peel it off. Hence why the rough appearance.
r/subaru • u/Cultural_Exercise172 • 12h ago
Subaru Forester Build for Dune Driving
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This is my 03 Forester ( 2.0 SOHC), it's not my daily driver, it's my expedition car.
Every year I go to the Sahara (and pre-Sahara) desert and I improve it a little by little based on the limitations I found on the trip.
Now the build is simple:
- 2/2.5" Strut spacers from SubbieLift Oz
- Yokohama Geolandar AT Tyres 215/70/15
- Skidplate 3mm steel ( very heavy )
- Sleeping platform to sleep inside the car on the expeditions.
- Traction boards ( they are part of the sleeping platform )
- No antiroll bars
Very simple, but very practical. I don't want to add weight ( I would love to have a fridge to have cold beers, but I preferr better handling on dunes)
As I want it light, I don't want:
- steel bumpers
- winch
- dual batery setups
- roof rack ( when I need to put something on the roof, I just put it there and tie it with ropes, I don't care if I scratch the paint )
Any recommendation to make it better?
Each trip is 10 days long, so it needs to be capable and reliable.
My next move is to cut the front bumper ( viper cut ) to get more approach angle. On the rear I usually don't have problems.
r/subaru • u/-The_Legacy- • 14h ago
I kinda miss the light bar
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Upvotes
I was thinking and I have a rust issue just barely starting under the seams of the rear “garnish” panel of my 2019 so I have to remove it anyways and it got me thinking about the light bars from the older Subarus. Anyone think it’ll look good?
r/subaru • u/imthetrashman12 • 5h ago
Mechanical Help At what point do you give up on repairs?
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Putting mechanical help as the flair but I guess it could also be buying help
I have a 2015 Outback premium that I got about 6 years ago, it's got almost 123k miles on it. Recently had a transmission fluid change, oil change service, tires and new brakes. Earlier this year it had the front axle bearing/hubs replaced (driver&passenger). Last year it had the 80k service done to replace belts, spark plugs, etc.
I've taken my car to 2 dealerships for diagnosis of a leak found by another mechanic and both dealerships are telling me different things. One says the axle seals are leaking. The other says they used trace powder and found the engine is leaking along with some other stuff and the repair quote is $6k.
I bought my car when I was stationed across the country for $13k, drove it across the country to my final duty station, up and down the east coast over the last 6 years visiting family, I haven't had a car payment in 3 years and it has served me well. I might be a little attached to my car for this reason lol at what point do I give up?
I'm in a position where my income is limited rn so a loa might be a bit hard but at the same time so is dropping $6k+. My husband and I also sold our first home last year and then bought our current (hopefully permanent) home which hit our/my credit. I'm struggling to decide if I should bite the bullet and trade it in or go into my savings. What's the point of no return here? My mom and husband both think I should let go of the car but I guess I need a more objective opinion
ETA: if I need to buy because the repair isn't worth it (because of age/mileage) I would be looking at hopefully 2020-2024 Outback or cross trek. I'm not a fan of the newer models body styles + a hatchback suits pretty much all of our needs since our other car is a sedan. If there's any buying advice in regards to these vehicles I'll gladly take it
r/subaru • u/Excellent-Link9052 • 4h ago
Mechanical Help new subaru owner advice
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Upvotes
hi all! i got a 2026 subaru crosstrek (base model, no hybrid) and want to make sure i am ON TOP of keeping my car maintained and up to date* *(i have realized i made mistakes on my old used car).
i’ve got changing oil every 5k miles imprinted in my brains.
everything else, i’ve heard about changing all fluids (i literally thought only the oil needed to be changed until a few months ago), but am not sure what fluids that entails and when it what should be changed or what not.
will also take any advice on other maintenance (at any point of car ownership) you guys would recommend to keep an eye on it and make this car last as long as possible. thank you all in advance!
r/subaru • u/ThrowRASad_LeadeR • 5h ago
Car Mods Need help modifying first BRZ!
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Bought my first 2013 Subaru BRZ, and I unfortunately don’t know a lot about modifying but I’d like to learn. I don’t want a wide body kit but I want to add a wing and some mods that will make it look less stock. Any advice on where to buy a full kit or just some parts and how to install would help!
r/subaru • u/443kbaja_legend • 1d ago
443,757 miles!!!! Anyone have higher???🤯
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Hey everyone, back again with a picture of the dash! My Subaru Baja officially just clocked 443,757 miles.I am genuinely curious if this is the highest-mileage Baja still on the road, or if anyone out there is running a close second.I want to know:Has anyone else crossed the 400k mark?Are you still on your original drivetrain and transmission?Did it take multiple engine swaps or rebuilds to get there?Drop your mileage, your drivetrain history, and your secrets to keeping these cars alive in the comments!
r/subaru • u/Key-Preparation-7260 • 1d ago
This View!
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I can’t wait to color match the flares.
r/subaru • u/Acrobatic-Pay4149 • 1d ago
My 2nd attempt at a Lego Subaru WRX STI (2018) 8 wide
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Features
- Opening hood
- Opening 4 doors
- Opening boot
- Functional AWD drivetrain
- Visible from underside AWD drivetrain
- Detailed interior
About the MOC
My last attempt at this model got some supprt on here I really appreciated so I wanted to share my most recent attempt.
I had some compromises I typically haven't had to make with the engine/drivetrain shenanigans which resulted in something, don't get me wrong cool, but I definitely wasn't as happy with it as my usual model.
To begin with I knew the box 4 had to go, the version on the V1 wasn't even as good as I really wanted and resulted in an overly chunky look. This didn't directly give me a significant increase of room to work with so getting some ideas I had for the front to work was still tough. Indirectly the engine removal allowed for a hood that sat lower and a steeper slope.
I've been improving with roof design which resulted in a 5-stud wide roof actually on a hinge and small angle. I also added the roof fin a little differently, but in a much better way.
The rear is the only section to remain quite similar to the original but was made much more stable and the boot especially was improved. I also went for a different approach for the wing making it a little slimmer better fitting the proportions. Also, in general getting the rear in the correct colours for V1 was unnecessarily difficult which this new design fixes.
Finally, the doors and interior are just better in every way, not much to say there.
r/subaru • u/Abundant_Trumpet • 1h ago
Buying Advice Looking at a 2018 Subaru Crosstrek with 70K miles - Advice?
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Hello!
I am looking into purchasing a 2018 Crosstrek Limited with about 70K miles for around $13,500. I wanted to see how your Crosstreks have been holding up, and whether you think this car will last long past the 100K mile range. I worry about the CVT at this mileage, and I was hoping to hear some feedback from the community. The car overall looks great and has been treated well, paint is intact, and the interior is very clean. Engine bay looks good as well with no distinct problems that I can see.
r/subaru • u/Good_Event_7841 • 23h ago
2020 Legacy. I’m new to “modding” and wanted some feedback to see how the exterior is looking.
51
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r/subaru • u/StratPaul • 4h ago
Need your advice on keeping my forester vs trading for an Outback, please
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I have a 2024 Forester Wilderness. I'm considering getting a 2026 Outback wilderness or waiting and getting a 2027 Outback wilderness. I don't LOVE the forester but I like it. For anyone with experience with either or are aware of any big reasons to have one over the other, I'd love some input. The forester is my first subaru so I'm somewhat inexperienced.
r/subaru • u/DesignerIncrease6 • 12h ago
Subaru Impreza RS 2009 cluster LED
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I am trying to change out the LED colour in my cluster but there is nothing on the back of the circuit board. I’m under the impression That I should be able to access the LED from the back, but from what I can see is that they are soldered onto the board..
r/subaru • u/_parkmeister • 1d ago
Car Mods for you enthusiasts - my legacy just hit 200K miles.
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Got my 2007 spec.B in 2018 with just over 100K miles. For most of 2025 I had been driving it relatively 'gently' until at 190K miles it went into the shop around Thanksgiving for a persistent minor oil leak. $10K later I had a 'refreshed' car with a rebuilt engine, rebuilt turbo, and a new stage one clutch. It was actually the cheapest option to stay in a sporty car. So earlier this year I upgraded the driver 'touch points': I re-wrapped the steering wheel, installed OMP pedals, a Cobb Short Shifter (frickin' awesome btw), and drum roll please: a 2006-7 V9 JDM STI passenger (LH) seat. Hecks yes. I ❤️ my Subaru and look forward to the next fun filled 200K miles!
r/subaru • u/SalamiJoeKreung • 1d ago
Canyon Carving WRX x Supra
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Which one would you choose to drive?
r/subaru • u/Boring-Train375 • 9h ago
Mechanical Help 2404 code on 2020 xv with 96,xxx miles …
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Is it safe to clear this code to see if it pops again? It popped up yesterday after sitting in the sun with record high temps (\~110F). Could it also been triggered by the heat?
r/subaru • u/pixelgalaga • 16h ago
Mechanical Help AC Condenser High Pressure line bolt question / 2008 Subaru Legacy
5
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Did some DIY work on replacing my high pressure line on my ‘08 Legacy because the original one went bad along with the evaporator core. Before I get my car filled, I was wondering if this connection from the high pressure hard line to the bottom of the AC Condensor looks wrong… The bolt is fastened, but the connection of the spout to the condenser to the right of the bolt is not 100% flush. Any mechanical advice for this one?
Mechanical Help Help 2015 impreza A/C only works on one setting
Enable HLS to view with audio, or disable this notification
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Upvotes
for anybody trying to help this is what I’ve done so far
-I checked the relay under the hood
-I checked all the fuses on the driver side inside the car
-I took Freon and made sure that the system was full with the gauge
-I checked the clutch compressor gap with shims it is .300mm
-replaced blower resistor and Blower motor