# Chevy Sonic 2016 Stalls at Traffic light coming off HWY **URL:** \ **Category:** Maintenance/Repairs\ **Created:** [September 29, 2025, 3:39am UTC](https://community.cartalk.com/t/chevy-sonic-2016-stalls-at-traffic-light-coming-off-hwy/204160 "2025-09-29T03:39:41Z")\ **Posts on this page:** 15\ **Page:** 1
**Author:** ![Brodieboy](https://avatars.discourse-cdn.com/v4/letter/b/3d9bf3/32.png) [@Brodieboy](https://community.cartalk.com/u/Brodieboy)\ **Post date:** [September 29, 2025, 3:39am UTC](https://community.cartalk.com/t/chevy-sonic-2016-stalls-at-traffic-light-coming-off-hwy/204160/1 "2025-09-29T03:39:41Z")
Hello, My car is like groundhog day with Bill Murray. Every morning I drive to work 10 miles on the highway. As I hit the the red light…it sputter and stalls. I start it and no problem off we go. This is the ONLY time it stalls during the day.This is EVERY DAY lol. Now it has thrown at times a P0171 lean code doing this so I can assume this is the problem. Once in awhile it throws a P0420 that the CAT might be acting up when on the HWY.. So far I have cleaned the throttle, checked for cracks at the accordion hose going from the throttle to the air filter box. I have changed the air filter. I have cleaned the MAF sensor and it responds accordingly with my OB2 scanner ( it doubled in value if I double the RPM’s). I thought maybe purge valve but it does not have any problems starting after adding gasoline.Starts right up.That is usually a hallmark symptom of the purge valve. Spark plugs shoulld be changed at this point because it is due base on mileage..I was thinking upstream or downstream O2 sensor but the live activity on my scanner while driving makes me not sure ( chagning accordingly). I have considered the dreaded PCV valve which is actually part of the valve cover and will probably be a real pain in the ■■■■ but… Like I said it does drive fairly well…I mean a little rough I guess but nothing big. And only stalls coming off the highway in the morning after driving 10 miles. There is a sligh downward incline to the traffic light but doubt that matters. Any ideas? Appreciate your time! ---
**Author:** ![oldtimer-11](https://avatars.discourse-cdn.com/v4/letter/o/e79b87/32.png) [@oldtimer-11](https://community.cartalk.com/u/oldtimer-11)\ **Post date:** [September 29, 2025, 6:21am UTC](https://community.cartalk.com/t/chevy-sonic-2016-stalls-at-traffic-light-coming-off-hwy/204160/2 "2025-09-29T06:21:10Z")
Since it i time to change plugs, change them now and see if it stops stalling. Check for vacuum leaks. ---
**Author:** ![SteveCBT](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/stevecbt/32/3192_2.png) [@SteveCBT](https://community.cartalk.com/u/SteveCBT)\ **Post date:** [September 29, 2025, 10:34am UTC](https://community.cartalk.com/t/chevy-sonic-2016-stalls-at-traffic-light-coming-off-hwy/204160/3 "2025-09-29T10:34:33Z")
Check your engine mounts. The left turn may shift the engine enough to pull something out of position ---
**Author:** ![glasspilot](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/glasspilot/32/27886_2.png) [@glasspilot](https://community.cartalk.com/u/glasspilot)\ **Post date:** [September 29, 2025, 10:51am UTC](https://community.cartalk.com/t/chevy-sonic-2016-stalls-at-traffic-light-coming-off-hwy/204160/4 "2025-09-29T10:51:41Z")
A left turn. You say when you add gas you’re ok. I’m thinking fuel pump combined with a tank low on fuel. In all modern cars the fuel pump is in the tank. If you’re lucky there’s a round hatch on top of the tank to access the pump. Remove the rear seat, if you’re lucky you’ll see the hatch. If you are handy it’s not that big of a job. Do it outside with all the windows down. Don’t smoke! Oh, I just remembered, replace the fuel filter. ---
**Author:** ![Tester](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/tester/32/15976_2.png) [@Tester](https://community.cartalk.com/u/Tester)\ **Post date:** [September 29, 2025, 1:45pm UTC](https://community.cartalk.com/t/chevy-sonic-2016-stalls-at-traffic-light-coming-off-hwy/204160/5 "2025-09-29T13:45:26Z")
> [@Brodieboy](#): > > Every morning I drive to work 10 miles on the highway. As I hit the cut off to turn left at the red light… A bad crank sensor can cause what you describe. > **[Bad Crankshaft Position Sensor Symptoms & Problems](https://www.1aauto.com/content/articles/bad-or-failing-crankshaft-position-sensor-symptoms)** > > Problems with the crankshaft sensor will often present as problems with engine timing. If you think your sensor has failed, here are some common symptoms of a bad crankshaft sensor that can help you in determining whether or not it has failed. Tester ---
**Author:** ![circuitsmith](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/circuitsmith/32/40376_2.png) [@circuitsmith](https://community.cartalk.com/u/circuitsmith)\ **Post date:** [September 29, 2025, 10:48pm UTC](https://community.cartalk.com/t/chevy-sonic-2016-stalls-at-traffic-light-coming-off-hwy/204160/6 "2025-09-29T22:48:19Z")
Cuts out as soon as you come to a full stop? Does this have an automatic trans with torque converter? Could be a sticky torque converter lockup clutch. ---
**Author:** ![Brodieboy](https://avatars.discourse-cdn.com/v4/letter/b/3d9bf3/32.png) [@Brodieboy](https://community.cartalk.com/u/Brodieboy)\ **Post date:** [September 30, 2025, 1:32am UTC](https://community.cartalk.com/t/chevy-sonic-2016-stalls-at-traffic-light-coming-off-hwy/204160/7 "2025-09-30T01:32:36Z")
I didn’t do a ■■■ job of clarifying. It is more idling at the traffic light. Could be going straight left or right. Sorry about that! ---
**Author:** ![Brodieboy](https://avatars.discourse-cdn.com/v4/letter/b/3d9bf3/32.png) [@Brodieboy](https://community.cartalk.com/u/Brodieboy)\ **Post date:** [September 30, 2025, 1:34am UTC](https://community.cartalk.com/t/chevy-sonic-2016-stalls-at-traffic-light-coming-off-hwy/204160/8 "2025-09-30T01:34:34Z")
Okay thanks My money is on a vacccum leak. The things I have been doing are to narrow a vaccum leak. ---
**Author:** ![Brodieboy](https://avatars.discourse-cdn.com/v4/letter/b/3d9bf3/32.png) [@Brodieboy](https://community.cartalk.com/u/Brodieboy)\ **Post date:** [September 30, 2025, 1:35am UTC](https://community.cartalk.com/t/chevy-sonic-2016-stalls-at-traffic-light-coming-off-hwy/204160/9 "2025-09-30T01:35:29Z")
No it sits there and idles for a minute or so . Then sputters..Then P0171 comes on and it dies. Definately a lean mixture problem. ---
**Author:** ![Brodieboy](https://avatars.discourse-cdn.com/v4/letter/b/3d9bf3/32.png) [@Brodieboy](https://community.cartalk.com/u/Brodieboy)\ **Post date:** [September 30, 2025, 1:37am UTC](https://community.cartalk.com/t/chevy-sonic-2016-stalls-at-traffic-light-coming-off-hwy/204160/10 "2025-09-30T01:37:32Z")
Hmm..Thank you. I will definately look into this. ---
**Author:** ![Brodieboy](https://avatars.discourse-cdn.com/v4/letter/b/3d9bf3/32.png) [@Brodieboy](https://community.cartalk.com/u/Brodieboy)\ **Post date:** [September 30, 2025, 1:39am UTC](https://community.cartalk.com/t/chevy-sonic-2016-stalls-at-traffic-light-coming-off-hwy/204160/11 "2025-09-30T01:39:58Z")
Sorry I should have just said a stop. It idels for a minute sputters and cuts out. Starts right up again though.Left tuen isn’t really a factor ---
**Author:** ![VOLVO-V70](https://avatars.discourse-cdn.com/v4/letter/v/8e8cbc/32.png) [@VOLVO-V70](https://community.cartalk.com/u/VOLVO-V70)\ **Post date:** [September 30, 2025, 1:42am UTC](https://community.cartalk.com/t/chevy-sonic-2016-stalls-at-traffic-light-coming-off-hwy/204160/12 "2025-09-30T01:42:49Z")
@Brodieboy Not really important but it not nessasry to reply to each person as everyone sees your posts so you don’t have to repeat yourself so much. ---
**Author:** ![Nevada\_545](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/nevada_545/32/41232_2.png) [@Nevada\_545](https://community.cartalk.com/u/Nevada_545)\ **Post date:** [September 30, 2025, 2:45am UTC](https://community.cartalk.com/t/chevy-sonic-2016-stalls-at-traffic-light-coming-off-hwy/204160/13 "2025-09-30T02:45:04Z")
P0171: Inspect the PCV crankcase pressure control diaphragm for leaks. Technical Service Bulletin [19-NA-114 1..2](https://static.nhtsa.gov/odi/tsbs/2019/MC-10161902-9999.pdf) ![image](https://global.discourse-cdn.com/cartalk/original/3X/d/5/d58e1bfee873f04cf6475306727892ef48fcee1e.jpeg) ---
**Author:** ![oldtimer-11](https://avatars.discourse-cdn.com/v4/letter/o/e79b87/32.png) [@oldtimer-11](https://community.cartalk.com/u/oldtimer-11)\ **Post date:** [September 30, 2025, 8:30am UTC](https://community.cartalk.com/t/chevy-sonic-2016-stalls-at-traffic-light-coming-off-hwy/204160/14 "2025-09-30T08:30:16Z")
```auto Use an uinlit propane torch slightly open. When you get it near the leak, the engine should smooth out or speed up. ``` ---
**Author:** ![glasspilot](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/glasspilot/32/27886_2.png) [@glasspilot](https://community.cartalk.com/u/glasspilot)\ **Post date:** [September 30, 2025, 11:12am UTC](https://community.cartalk.com/t/chevy-sonic-2016-stalls-at-traffic-light-coming-off-hwy/204160/15 "2025-09-30T11:12:32Z")
Brodie, I still think you have to consider fuel delivery problems. Also I agree with looking for a vacuum leak.