* Weak fuel pump. A weak fuel pump can't provide enough fuel to the engine, especially when it's under a load, such as when going up a hill.
* Faulty oxygen sensor. An oxygen sensor monitors the amount of oxygen in the exhaust gas and sends a signal to the engine control unit (ECU). The ECU uses this signal to adjust the air-fuel mixture. A faulty oxygen sensor can cause the engine to run too lean or too rich, which can cause it to stall.
* Dirty or faulty spark plugs. Dirty or faulty spark plugs can't create a strong enough spark to ignite the air-fuel mixture in the cylinders. This can cause the engine to misfire or stall.
* Vacuum leak. A vacuum leak can cause the engine to run lean, which can cause it to stall.
* Head gasket leak. A head gasket leak can cause the engine to lose compression, which can cause it to stall.
* Transmission problems. A faulty transmission can cause the car to stall when it shifts gears.
