2019 Subaru Forester Powertrain & Transmission Problems

The electrical system fails, and the battery is not charging sufficiently. When the auto start/stop engages, the car does not restart in traffic. Requested a battery test at the dealership in May 2025; was told it could not be done that day because it would require leaving the dealer service shop. Eventually, the electrical system became unstable, and the car stopped in traffic on 11/07/2025. Replaced battery following OEM specs. In February 2026, symptoms reappeared with a new battery failing on 02/15/2026, resulting in all saftey systems failing in traffic when auto start/stop enages.

50k Mileage Mark: When the vehicle turned off at the stop light to save gas, the car stalled. I had to frequently put the car back in Park, and restart the engine. Since then, I had to turn off the “auto turn off” function for fear of the car stalling on the road. This has caused unnecessary anxiety and fear while driving, harming my psychological wellness. Since the 50k mark this has happened about 10 times. The most recent issue was this month

- *Incident 1 (2023):* While driving, my vehicle suddenly stopped while in drive gear, accompanied by a high-pitched alarm and multiple engine service lights. It took over 30 seconds to shift into park and restart the vehicle. The incident occurred at an intersection, and I was fortunate to avoid any collisions. - *Incident 2 (September 2025):* The same problem recurred on two separate occasions- AFTER CERTIFIED REPAIRS. The vehicle came to a complete stop while driving uphill at a decelerated speed, and also while stopped at an intersection. In both instances, the gear was in drive, and the vehicle shut down completely, displaying engine service lights. *Previous Repairs:* - *TCV Replacement:* The Thermo Control Valve was replaced under warranty due to a faulty issue affecting the EyeSight system. - *Battery Replacement:* The battery was replaced under warranty in 2023 after the initial incident. Whats concerning is that my dealer said to have found an “after market” appliance hooked up. This said feature was placed by certified subaru dealership when vehicle was purchased. This said item was never identified as to causing the said issue. Which raised even more safety concerns.

CVT Transmission failed and not repairable. 6 months out of warranty but under mileage for warranty at 37,000 miles. Fairly new vehicle that is useless w/o $9,000 for a replacement transmission. Exact same defect in 2018 and older models that Subaru is covering repairs and extended warranty for those years.

While at a Stop as the engine turns off and awaits decompression of brake to turn on again vehicle moves forward bit, then the engine shuts down while in drive (stalls) had a vehicle hit me in rear but luckily I had my trailer hitch on because it saved me from body damage . I had to place in park and restart this has happened several times before and I’m kinda nervous and makes my wife nervous when stopping at lights or stop signs it might turn off in the middle of the intersection. When this occurrence happens all dash lights pop up … I checked engine with code reader after the incidents but it doesn’t give out any info on what could possibly be happening. I had the Dealership change the Thermo control module in 2025 but these occurrences has happened before and after the TCM replacement.Having the dealership check is like wasting my time and money because they aren’t able to pinpoint the cause without a code . There has to be a problem somewhere in the system it’s just that the dealership in Hawaii has no clue ..

Subaru Transmission is wonky! Makes noise... Feels unsafe... sent to shop... they say it needs a new transmission

On April 16, 2024 the Thermo Control Valve on my 2019 Subaru Forester failed while I was going 70 mph in the middle lane of rush hour traffic. All of the warning lights came on at once as my engine stalled. I lost all mechanical power and was barely able to make it off the highway without getting hit. There was no prior warning that the Thermo Control Valve was bad. I had the car serviced at a Subaru dealership three weeks before the incident and was told that everything looked good on my car. The dealership replaced the Thermo Control Valve under extended warranty coverage. I have a second 2019 Subaru Forester that also falls in this group of vehicles, but Subaru will not replace the Thermo Control Valve until it fails.

While driving on a highway outside Milford, CT my vehicle is check engine light suddenly illuminated. I had a sudden loss of power, no heat, and the engine temperature was unable to read. Engine temperature was not accurately reporting and showed it as being cold as indicated by blue light warmup light. My eyesight, pre-collision system, and sport mode was disabled due to the engine light being illuminated. The vehicle was seen at a Subaru dealer, who diagnosed the issue to be the thermo control valve. Dealership informed me that it was unsafe to drive and I risk complete engine failure, overheating, and or fire if I continue to operate without required repair. As a result, I was stranded overnight, three hours away from home. Repair was completed on [XXX] at cost of $1830. I learned at the dealership that this is a known issue, in 2021 Subaru replace the plastic components of this part with aluminum due to similar issues experience by many customers. Customers are reporting vehicles going into “limp mode” and even engine damage. I learn that there is a class action lawsuit regarding the same issue, which can be reviewed here: [XXX] Please help to recall vehicles and push Subaru to repair/refund. INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6)

Check engine light came on and gave code P26A6 which came back the thermal control valve which is a well known issue with this make and model vehicle.

Power Control Valve malfunctioning at 26,000 miles. Causing all safety features (auto braking & lane departure) to be shut off.

Defective/failed thermal control valve. Valve failed while I was driving, resulting in safety systems (e.g., lane keep assist, pre-collision braking). Looking this up, this is a known issue to Subaru.

My wife was driving her 2019 Subaru Forester (purchased new) and the Eyesight disabled and the check engine light came on. The car was still running, but not as it normally would. It had less power but would still maintain the speed limit. At home the car idled differently, like it was running too rich or too lean. The exhaust also smelled funny.

When driving, ALL lights on the dash went on and vehicle safety features did not work- no cruise control, automatic breaking, automatic headlight adjustments, etc. We were over 500 miles from home and had the oil changed but it did not fix the problem. Had $72,000 miles on it, 4 years old. We had to drive home that distance to get it repaired over a 2-3 day period. No safety features were enabled as we drove. Thermo Control Valve was deemed faulty and replaced. Seeing after the fact that the TSB was issued without any VIN numbers: [XXX] , I believe it should include our VIN number and be recalled and the replacement paid for. INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6)

On June 20, 2023, the "check engine" light came on my 2019 Subaru Forester and "Eyesight" flashed on my dashboard as disabled. I immediately went to my mechanic and he ran a diagnostic which showed the following: "P26A3 - Engine Coolant Bypass Valve." My car has 75,000 miles and is out of warranty for the powertrain. In reviewing online forums, this problem is a recurring one that is affecting many Subaru owners. The cost is $1,200 to $1,500 to fix. I believe this should be a recall issue. Other drivers have noted sudden engine shutoff but I have not experienced that yet. The car is currently in the shop. Subaru knows this is a problem.

Was driving in the right-hand lane on the interstate with the cruise control set, went to change lanes as I was approaching a slower moving semi truck going up an incline. Cruise control deactivated with no inputs from myself. Vehicle began to decelerate. Looked at instrument cluster, the Check Engine Light was on along with Eye Sight Off symbol. Additional symbols for forward collision avoidance and rear active braking were also on. No warning signs were present prior to the cruise control turning off. The unexpected loss of power increases the risk of collision while traveling on the highway. Vehicle was taken a Subaru dealer, diagnosed with code P2682, Coolant Bypass valve performance, with a recommendation to replace the coolant bypass valve.

Eye-sight system shutdown and the car, although it was drivable, ran rough. Since there is a huge reliance on the monitors as they are designed to "forward think" to aid the driver, this was a major disruption to the driving experience. Not knowing what the disabled components affected, was a huge cause for alarm. Upon seeing the check engine light come, my wife brought the car home and I hooked up my device to read the code (P26A3 - showed up). Then I looked up that code and was directed to multiple incidents where that very same thing has become frequent on this model and a few others like it. We called the Winston-Salem NC Subaru Dealer (Flow) and they suggested we bring the Forester in for a check. Once they checked the vehicle out and confirmed the code we mentioned, they told us the "TCV" problem was found on our vehicle and they have seen others with the same problem. They even had the parts in stock to make the repair that day! They kept the parts and said they were going to be sent back to Subaru of America for analysis.Interesting detail: once we drove the repaired vehicle, it ran better than it ever had and the only work they did was to fix the TCV issue (according to the repair paperwork).

The Thermo Control Valve had went out. When the valve went out, the Subaru Eyesight became disabled. This also turned off the forward collision, automatic emergency braking, blind spot warning, lane departure, and rear cross traffic warning and braking. Subaru has a service bulletin, 09-80-21, stating the issue.

Auto safety systems compromised with illumination of check engine light and engine temp warning light. Subaru dealership service department determined problem with Thermo Control Valve. Engine was not overheating as the vehicle was being driven in winter time, February in Alaska. Only indication of problem was indicator lights and reduced heat from cabin heat system. Vehicle went into "limp" mode as soon as warning lights illuminated, disabling advanced safety systems.

Driving uphill when the car suddenly jolted, lost power, and all warning lights became illuminated. All safety features were disabled as well. The sudden stop almost resulted in being rear ended and the car was barely drivable afterwards. Diagnostic trouble codes: P26A6, P2004, P2005, P060B, P0191, P24B9, P2200, P2400.

On January 1, my wife was returning home from a grocery run when our 2019 Forester’s dashboard suddenly lit up like a Christmas tree--Check Engine, EyeSight, Anti-Lock Brakes, Anti-Skid, and blue Temperature lights all came on simultaneously. The Forester did not lose any appreciable power but the heater stopped working and was only blowing cold air. My wife was only a couple of miles away and brought it straight home. I checked under the hood but had no idea what was going on, so I drove it over to my local Autozone for a scan, and it came back with the 'P26A3' Code, as well as 'P3300,' and 'P2100' (Throttle Control Motor-Circuit Open). I brought our Forester back home, did some online research, and discovered that this code typically indicates a thermal control valve assembly (TCVA) failure. Our vehicle's 60,000-mile powertrain warranty had just expired but fortunately, we live near a reputable repair shop which was able to take the Forester in the next day, confirm the codes and TVCA failure, and then make the repair. Further research revealed that this appears to be a widespread quality control problem and typically costs affected owners between $1,100 and $2,000 to fix beyond the expired standard 35,000 mile /60,0000 mile powertrain warranties. In fact, there is a Subaru Forester Owners thread that runs over 33 pages with 654 posts from other owners throughout the world reporting the very same failure over the past year, nearly always between 50,000 and 70,000 miles. (https://www.subaruforester.org/threads/2019-thermo-control-valve-assembly-and-warranty-merged-thread.823510/) This past week, a friend of mine who's an old school mechanic, took the old TCVA apart and discovered that coolant had actually leaked into the part's internal electronics and shorted them out, causing the failure. He was amazed that the short circuit did not damage my Forester's computer. It's certainly a design and manufacturing defect and a recall should be issued by Subaru.