2020 Forester Sport acting up… dealer has no clue what is wrong

I got a 2020 Forester brand new from a dealership in September 2020. I’ve done every maintenance check at the same place, always on time. Only things that weren’t done there were some hail damage repairs and a few windshield replacements (four so far). Insurance set up the bodywork, and the windshields were replaced at Safelite.

Last oil change, tire rotation, and regular maintenance were in early December. Since then, I’ve only driven about 1,000 miles. This past Sunday, I was just 1.5 miles from home when every warning light on the dash turned on—messages about auto stop/start, EyeSight, and other systems shutting off. Pulled over, and the car stalled. It wouldn’t accelerate, and I couldn’t shift gears. Had to use the manual gear release to get it into neutral and move it onto the shoulder. Got it towed to the dealer, and now they’ve had it for days with no idea what’s wrong. They’re talking about extra charges just for figuring it out.

The only other issue I’ve had before this was the auto stop/start not working. The dealership said it was just loose battery terminals, which made sense because I had disconnected the battery a while back to reset the rear hatch.

Anyone got any ideas? Appreciate any help.

How old is the battery?

Caiden said:
How old is the battery?

Still the original one.

Could be the thermo control valve?

Murphy said:
Could be the thermo control valve?

That was my guess too. At first, I thought the CVT was done for, but that should be easier to diagnose.

Moe said:

Murphy said:
Could be the thermo control valve?

That was my guess too. At first, I thought the CVT was done for, but that should be easier to diagnose.

Honestly, sounds like the dealer is dragging this out. They have all your service history, so they should be able to figure it out by now. Did they pull any error codes?

@Murphy
Yeah, and here’s the kicker… They said there are ‘over 100 lost communication codes’ in the system. But if that’s the case, why didn’t they notice anything during my last service in December?

Moe said:
@Murphy
Yeah, and here’s the kicker… They said there are ‘over 100 lost communication codes’ in the system. But if that’s the case, why didn’t they notice anything during my last service in December?

Wow. You might need to get Subaru corporate involved.

@Murphy
Ever dealt with them before? I feel like Subaru should be able to figure out their own cars. Just don’t want to come off as angry or difficult.

Moe said:
@Murphy
Ever dealt with them before? I feel like Subaru should be able to figure out their own cars. Just don’t want to come off as angry or difficult.

Not with Subaru, but I had to with Toyota once. They sent a top-level mechanic, but I still ended up diagnosing the problem myself. You’ll be fine as long as you stay calm. You still need their help at the end of the day.

@Murphy
Appreciate the advice. I’ll update once I hear back from them.

Moe said:
@Murphy
Yeah, and here’s the kicker… They said there are ‘over 100 lost communication codes’ in the system. But if that’s the case, why didn’t they notice anything during my last service in December?

That means absolutely nothing… This dealership sounds clueless.

At this point, I’d reach out to Subaru corporate. If the dealer starts charging you just to diagnose it, you might be able to get that covered. Make sure you have records of every service visit and notes from the mechanics.

@Oswin
Thanks :pray: I’ll follow up with them tomorrow and see what they say.

A bad thermo control valve can cause some weird issues. If it shorts out, it can take out the power supply for things like the throttle body, pressure sensors, and a few other parts. First time I saw it happen, it had everyone scratching their heads. The dealer should check that first.

@Darby
Thanks! I’ll mention that when I call them tomorrow. I was reading about it in other people’s posts on this forum, but I wanted to see what the dealer said first.

How many miles on it? Is this the first big issue?

Dax said:
How many miles on it? Is this the first big issue?

96k miles. Only other issue was around 87k when auto stop/start kept stalling at red lights. Had to shift into park and restart the car. Dealer couldn’t figure it out at first, then said the battery sensor bolt wasn’t tight enough. That actually made sense because I had disconnected the battery a couple months earlier.

Had a few times where the rear hatch wouldn’t close properly—seems to be some kind of electrical issue. Other than that, just windshield damage from rocks on the road.

Man, I’ve been through something similar. Had a 2018 Outback—loved it, but after a year, weird engine issues started popping up. Dealership said nothing was wrong. Then, during the lockdown in 2020, my battery kept dying. Went through roadside assistance multiple times, replaced the battery, but the problem kept happening. Dealer had it for two weeks, replaced the battery again, told me it was fixed… I went to pick it up, and it was dead in the parking lot.

They kept it another two weeks and still couldn’t figure it out. Eventually, I traded it in for a 2020 Forester (got screwed on the trade-in since they rolled my Outback loan into it). Loved the Forester for a while, then auto stop/start quit working. Took it in, and they had to replace the CVT. A year later, same issue—this time, they replaced the starter and thermo control valve.

That stop/start feature messes with the engine way too much. I disable it every time I get in the car now. They really need to get rid of that system.

Check for rodent damage. Squirrels or mice love chewing on wires.