2014 Subaru Legacy stalled while driving

Hi folks,

I just bought a used Legacy about a week ago. No issues at all until today when it stalled while I was driving. It's pretty cold here in Minnesota, but I had been driving for abut 20 minutes and the engine was warmed up. It did start back up again and no check engine lights at all. It only has about 59,500 miles on it. Any ideas what the issue might be? I know fuel filter could be a problem, but it seems early for that to be so dirty it's causing stalling issues. I was also reading that a dirty mass airflow sensor can also cause stalls?

Thanks for any advice!

Did it stall while you were idling or while you were actually in motion? I am no mechanic, but I did have this issue with a previous vehicle (not a Subaru) and it happened while idling.

The throttle body seemed to be the issue, the idle seemed to wander after the car was warmed-up and ECU went into closed-loop control. I replaced the whole assembly (throttle body, position sensor, actuator) since it did not seem to be a serviceable part. This fixed my problem.

Did it stall while you were idling or while you were actually in motion? I am no mechanic, but I did have this issue with a previous vehicle (not a Subaru) and it happened while idling.

 

The throttle body seemed to be the issue, the idle seemed to wander after the car was warmed-up and ECU went into closed-loop control. I replaced the whole assembly (throttle body, position sensor, actuator) since it did not seem to be a serviceable part. This fixed my problem.

No, it was actually while I was braking - probably going between 35-40. The idle has seemed steady otherwise.

Are you using cheap gas? I don't think you should be having fuel filter issues with that low of mileage.

Yeah, the more I think about it the fuel filter probably isn't the culprit. I got gas a few days ago, and it was from a normal gas station, a Holiday I think. I was reading on another forum that Subaru models from about 2010-2016 can have a problem with the CVT that causes the car to stall while braking. Really hoping this isn't it!

Id look for a vacuum leak.

I once had a small vacuum line come loose on the intake plenum and I was randomly stalling until I found it.

One other thing I noticed is that the car is only getting 19.2 mpg - which seems pretty low. It's a 2.5i and should be doing 25mpg even at 100% city driving (probably 60/40 split city/highway driving).

That's almost exactly what mine got before I sold it. I drove it mainly to high school and on the highway a few times a week. In the winter months your gas mileage typically should go down due to many things (such as switching to a winter gas blend, tire pressures changing rapidly, your car driving at higher RPMs to warm up, etc.).

That's almost exactly what mine got before I sold it. I drove it mainly to high school and on the highway a few times a week. In the winter months your gas mileage typically should go down due to many things (such as switching to a winter gas blend, tire pressures changing rapidly, your car driving at higher RPMs to warm up, etc.).

Thanks, that's helpful to know. Trying to figure out if anything else is behaving abnormally to help pinpoint where the stalling issue is coming from.

Id look for a vacuum leak.

 

I once had a small vacuum line come loose on the intake plenum and I was randomly stalling until I found it.

Thanks for the tip. Definitely something to look at. Did you have a check engine light on at all or no?

It didn't trigger a CEL for me.

The stalling was really annoying though, I stalled taking off at the traffic lights (5EAT gearbox in my car, not manual) and the person behind me drove right into me without looking. Took a week to get the car back from the repair shop.

Glad you got it fixed and within the 10/100k warranty! I recall the 2010-2011 had torque converter issues causing stalling, didn’t know newer models were susceptible.

https://legacygt.com/forums/showthread.php/vehicle-stalls-out-after-hard-stop-192557.html?t=192557