Fix an Engine Stalling at Idle

Easy step by step guide on how to repair an automotive engine that stalls at idle, this information is presented in order of popularity and pertains to most vehicles.

Difficulty Scale: 4 of 10

Begin with the vehicle on level ground engine off (cold) with the emergency brake set.

The "check engine" warning lamp is warning the driver there is a problem which could pertain to the engine stalling at idle. Learn more

Check Engine Light MIL

Step 1 - When a vacuum hose breaks or cracks it can fall off causing the engine to lose vacuum and stall at idle. Vacuum hoses are meant to transfer engine vacuum to various accessories such as a brake power booster.  Learn more

Broken Vacuum Line

Step 2 - If an air intake boot becomes torn or disconnected it will cause the engine to stall at idle. An air intake boot is used to transfer air from the mass air flow sensor to the throttle actuator.  Learn more

Air Intake Boot

Step 3 - When an idle air control valve fails it will cause the engine to stall at idle. On an older engine, an idle air control motor is responsible for setting the idle speed of the engine.  Learn more

Idle Air Control Valve

Step 4 - Coking is a tar like substance impedes air flow which disrupts the integrity of the computer system and can cause the engine to stall, and may have hard starting as well, this condition naturally occurs in the intake system of over time.  Learn more

Coking Condition

Step 5 - When a EGR (exhaust gas recirculation) valve sticks open, it allows exhaust gases to enter the intake system effectively causing a large vacuum leak which will cause the engine to stall at idle. Older engine's are designed with an EGR valve (exhaust gas recirculation) that allows exhaust gas to enter the intake manifold at cruising speeds. 

EGR Valve

Step 6 - Automatic transmissions are equipped with a torque converter that can fail which will cause the engine to stall by not allowing the engine to become disengaged from the engine at a stop. This condition will usually start to occur after long a drive on a freeway, the car will shutter as it stalls coming to a stop.

Torque Converter Cutaway