Yes, a broken AIS can absolutely cause a car not to start. The AIS, or Air Intake Solenoid, is a critical component of a car's idle air control system. It regulates the amount of air that bypasses the throttle plate when the engine is idling. When you turn the key to start the engine, the vehicle's computer (ECU) expects a specific air-to-fuel ratio. A malfunctioning AIS can disrupt this balance, leading to a condition that is either too rich (too much fuel) or too lean (too much air), preventing the engine from firing up.
While a faulty AIS is a common culprit, it's important to diagnose the issue correctly as other problems can mimic its symptoms. A no-start condition is typically related to issues in three main areas: fuel delivery, ignition/spark, or air intake/compression. The AIS falls into the air intake category. Before replacing the AIS, it's wise to check for simpler issues like a dead battery, faulty starter motor, or empty gas tank. A professional mechanic can use an OBD-II scanner to read trouble codes from the ECU, which often point directly to a problem with the idle air control circuit, confirming the AIS as the source of the problem.
Here are common symptoms and their relation to a faulty AIS:
| Symptom | Why It Happens with a Bad AIS |
|---|
| Engine cranks but won't start | The ECU cannot adjust the air intake for startup, creating an incorrect air-fuel mixture. |
| Rough idling or stalling immediately after starting | The solenoid is stuck in one position, unable to maintain proper idle RPM. |
| Check Engine Light is on | The ECU detects an irregularity in the idle air control circuit and logs a code (e.g., P0505). |
| Unusual hissing sound from the engine bay | A vacuum leak caused by a stuck-open AIS valve. |
| Engine starts only when pressing the gas pedal | Manually opening the throttle bypasses the faulty AIS, allowing air in. |
Replacing an AIS is generally a straightforward repair. However, if the car exhibits a no-crank situation (where you turn the key and hear nothing), the problem is almost certainly unrelated to the AIS and points to the battery, starter, or ignition switch.
