- Idle Air Control (IAC) valve - The IAC valve controls the amount of air that bypasses the throttle plate when the engine is idling. If the IAC valve is dirty or faulty, it can cause the engine to stall when the throttle is closed, such as when the car is idling at a stop sign or light.
- Throttle Position Sensor (TPS) - The TPS sends a signal to the engine's computer (ECU) indicating the position of the throttle plate. If the TPS is faulty, it can send an incorrect signal to the ECU, which can cause the engine to stall.
- Oxygen Sensor - The oxygen sensor monitors the amount of oxygen in the exhaust gas and sends a signal to the ECU. If the oxygen sensor is faulty, it can send an incorrect signal to the ECU, which can cause the engine to stall.
- Fuel Filter - A clogged fuel filter can restrict the flow of fuel to the engine, causing it to stall.
- Fuel Pump - A failing fuel pump can also cause the engine to stall, especially when the fuel tank is low.
- Vacuum Leak - A vacuum leak can cause the engine to stall by allowing unmetered air to enter the engine.
- Electrical Problem - A loose or faulty electrical connection can also cause the engine to stall.
Troubleshooting:
If your 1998 Honda Civic is dying out at stop signs and lights, you should start by checking the IAC valve and the TPS. You can clean the IAC valve with a throttle body cleaner and check the TPS with a multimeter. If the IAC valve or TPS is faulty, you will need to replace it.
If the IAC valve and TPS are not the cause of the problem, you should have a qualified mechanic diagnose the problem.
