Honda Accord 1999

Two months ago I noticed my car swtiching off while I am driving. One time I was driving on the highway up to 65 miles per hour, AC was on, all over sudden the car shut off, didn’t completely stopp, restart itself and continued. This happened couple of times. And then sometimes it stops while i am on the trafic light. I took it to the machanic, they said it needed full tune up, they have done so, but i am seeing the same problem again. My check engine light is one, I took it to the guy back, he thinks it is to do with the AC, but the car shuts off sometime while the AC is off. Any ideas, pleae help?

Sounds like someone has been seriously guessing. A “tune-up” or lack thereof, is not going to cause your car to quit spontaneously.

Since it sounds like your car sputters when it quits, my guess is the main relay, which powers the fuel pump, is acting up.
It’s also possible the fuel pump could be failing. A worn pump draws more electrical current. This translates to more heat and over time can cause relay contact points to burn, so they’re related.

The relay is easy; change that and see what happens.

About 15 years ago, I had a problem similar to this with a Saab 900. The problem turned out to be a faulty “Hall sensor”. I do not know if your car has a Hall sensor, but perhaps it would be good to suggest this to your repair person.

I had similar problems with my '89 Accord LX-I several years ago, the engine randomly stopping. This occurred very intermittently. Sometimes, it was immediately after starting the engine. It would die. Then, you could immediately restart it. The engine stopped once while I was driving on the freeway. I could not roll down the windows to signal a lane change as turn signal(s) did not work; dash lights were off.

I traced the cause to burnt contacts in the electrical portion of the ignition switch. This harness attaches to the back of the mechanical ignition key switch.

It was a relative easy repair, about an hour. There was some disassembly necessary to remove a dash panel and cover on the upper portion of the steering column.

Insure that the battery is disconnected before you start this repair.

Good luck!

Captain Jack