2004 Mazda 3 Intermittent Stalling

Hi, I’m the proud owner of a very rusty 2004 Mazda 3 with about 75,000 miles. I bought this car for $1,000 to take me 5 miles back and forth to work 5 days a week. The car has been stalling intermittently as I come to a stop in traffic. I took it to a mechanic and they were not able to replicate the problem. The check engine light is not on although it has been on in the past. Service history indicates that the care might have a faulty engine temp sensor as this was the source of a previous check engine light. The previous owner elected not to replace the sensor since it was not causing any symptoms. Could this be the cause of the intermittent stalling? It seems to happen only when the engine is cold and the outside temperature is very cold. Although given that I only drive the car about 2.5 miles each way to work the engine never really has a chance to warm all the way up. Any help you knowledgeable people could give me would be greatly appreciated. Despite the rust I do love this car. Thanks!

The problem might be with a dirty electronic throttle body.


Get some throttle body cleaner and try cleaning the throttle body.

If you do this, don’t push the throttle plate open. Instead have someone get in the car, turn the ignition on, and then push the gas pedal to the floor.

The computer will then command the throttle plate to open so the throttle body can be cleaned.


Just to clarify @Tester, do you mean to turn the key to the “run” position, not to actually start the car? Just wanted to make sure the OP knew not to start the car if they were not supposed to.

Tester’s guess above is where I’d start too. That’s a common cause for stalling at stop lights. The engine coolant temp sensor provides critical info determining the air/fuel ratio, so if it tests bad it must be replaced. Although I doubt that’s the cause of the stalling, unless it is an after-effect of carbon build up from too rich operation. If the engine is behind schedule on its routine maintenance , that could explain the symptom too.

Thank you everyone for your suggestions. I’ll start by trying to clean the throttle body.