2020 Subaru Ascent: adaptive cruise control problems

Filed Dec 12, 2025 · AK

Vehicle: 2020 Subaru Ascent Issue: Cold weather software glitch If you are operating an Ascent or possibly other Subarus with the CVT in temperatures below -20F be certain to have either a small wrench or the appropriate size socket to loosen the ground clamp on the battery ground cable with you so you can employ what I call the magic Windows fix wherin one completely de-powers the system and reboots it. With all the ridiculous interconnections, if the CVT temperature sensor thinks the tranny is too cold the cars operating system looses it mind and goes completely bonkers. Subaru obviously did no cold weather testing. We have had 2 failures in cold weather. It only happens at temperatures well below the-20F range. The first case happened last year while driving after being stopped for a couple of hours. Everything seemed normal and then suddenly several warning lights came on and all of the safety systems and the eyesight system shut down. The car ran and drove, but none of the associated systems would work. No traction control. No cruise control. Several other systems. The only solution was to disconnect the battery and get this rolling computer to reboot. This was a temporary fix as the condition repeated itself although the car was driveable but with none of the safety systems operational. This year we were out in cold weather, -25 to -32. We went to a place to have lunch and when I went to restart the car the app failed to do so. So I put on all my gear and went out to start it manually. It would not start and all the warning lights were on and the radiator fan was running full tilt at -25F with the car off. I tried twice to get it going by pulling the battery cable to get it to reboot. Evidently when this happens you must leave the battery disconnected long enough (about 5 minutes) for all the capacitors in the electronics to drain. Once restarted, the car drove normally but we did not shut it down for any reason for the rest of the day.

Filed Feb 19, 2025 · Transmission · OR

Ever since our car went in for re-programing CVT drive chain it progressively has been having a problem of something slipping in drive and in cruise control. feels like a loss of power and a feeling chatter from transmission. Now when you put it in drive it makes a jerking noise. the thing is that we never had this problem until it went in for this recall. it's been back twice and they claim they can't find any problem but continues to get worse. it happens every time we drive it . just returned a 700 mile trip and it's very annoying. Also we do have an extended warranty.

Filed Mar 6, 2024 · Driver assistance · CA

Right front camera is blocked by plastic since manufacture. The adaptive cruise control and forward emergency braking do not work reliably unless the object is the left visual field. My car will accelerate into a car in front with no emergency braking. No accident. so far, because I have been able to avoid accidents by braking myself. The problem was diagnosed by Diablo Subaru of Walnut Creek. The vehicle was inspected and diagnosed by a Subaru dealership. The car tells me it cannot see the car in front. It also says it cannot see anything on haphazard basis. But it will also accelerate toward cars in front of it at close range because it cannot see.

Filed Jun 21, 2022 · Driver assistance · 10,000 miles · VA

The contact owns a 2020 Subaru Ascent. The contact stated that while driving at an undisclosed speed with the cruise control activated, the vehicle experienced phantom braking. The vehicle was taken to the dealer where it was diagnosed that the vehicle performed as designed. The vehicle was not repaired. The manufacturer was not made aware of the failure. The failure mileage was approximately 10,000.

Filed Oct 20, 2020 · Electrical · 3,600 miles · CO

2 episodes of disabled 2020 subaru ascent touring in 4 months after purchasing it new. Currently only has 3600 miles on it. 1. Car would not start from stationary position because both my electronic key fobs were in the car at the same time. Towed to dealer. They found my 'missing' key fob. 2. Battery died while stationary, waiting at vet 25 min., listening to radio while car was otherwise 'off'. Only it did not die a clean death but continued a zombie existence: A/C came on and off at full speed, arbitrarily; actually could not shut down the car kept acting electrically crazy with various lights on dash coming on and off; 3. Could work the power windows while the battery was 'dead' , windows would go down but only came partway back up; for some 40 minutes we heard a beep in a morse code sort of irregular manner from interior rear aspect of car; dash would click from time arbitrarily, sounded like the click heard during cruise control when approaching a vehicle ahead, the 'adaptable' feature, or perhaps the click heard when switching from high beam to low beam lights. I don't feel I can rely on this car not dying. Very upset, and very disappointing.

Filed Feb 18, 2020 · Acceleration, Electrical · 1,200 miles · CA

Vehicle eyesight safety system (adapative cruise control), lane departure and anti collision systems deactivated while driving. Vehicle backup camera failed while in reverse.