Car stalls when braking...but only in warm weather



I have a 2005 Hyundai Sonata. It has about 31,000 miles on it. I have had it for about a year. I noticed last year that it would occasionally stall when I braked. This happened about 6 times. It was annoying but not serious. I noted that most times the engine would not actually stall until I removed my foot from the brake. It idled fine in drive while the brake was on, but once I released the brake pedal it stalled. Then fall came and it got cooler. It didn’t happen to me at all again until this week, when NY temps got above 80 again. Apparently this stalling thing is only happening in warm temps…above 80 degrees, and even then it doesn’t happen every time I brake. Once or twice a day at most-and sometimes not at all. Does anyone have any ideas as to what might be the cause?


I think you have an internal vacuum leak in the power brake booster.


Typically, this is the sign of a bad brake booster. The power brakes on this car is powered by engine vacuum through a big vacuum line. But, if the booster goes bad, it can cause a vacuum leak that will stall the engine. Most problems like this happen when the brakes are applied, and it opens a leak. But, it can also happen when the brakes are released, and the leak can open then.

This car should still be under warranty. Have the dealer fix it.


I have the same issue with my 2005 Tucson V6 4WD. After it’s warmed up (about 45 minutes) It stalls when I come up to a red light. It drops down to 500 rpm then dies. This happens with or without AC. If I coast up to the light in Neutral, it doesn’t die. Right turns seem to aggravate it too. It does seem to be related to outside temperature as well. The hotter it gets the more it stalls. It got so bad today I had to take it to the dealer. I don’t have much confidence in them. It isn’t covered by warranty either. Wish me luck