* Mass Air Flow (MAF) Sensor: This sensor measures the amount of air entering the engine. A faulty MAF sensor can provide inaccurate readings, leading to a lean fuel mixture (too much air, not enough fuel), resulting in low idle and stalling.
* Throttle Position Sensor (TPS): This sensor tells the engine control module (ECM) the position of the throttle plate. A faulty TPS can provide incorrect signals, causing the engine to receive improper fuel delivery, resulting in low idle or stalling.
* Idle Air Control (IAC) Valve: This valve regulates the amount of air entering the engine at idle. A dirty or faulty IAC valve can't properly control the air intake, leading to low idle and stalling.
* Manifold Absolute Pressure (MAP) Sensor: This sensor measures the pressure in the intake manifold. An inaccurate reading can lead to incorrect fuel delivery, similar to a faulty MAF sensor.
* Crankshaft Position Sensor (CKP) Sensor: While less likely to directly cause *only* low idle, a failing CKP sensor can cause erratic engine behavior including stalling, misfires, and poor idle. It's crucial for proper ignition timing.
* Oxygen (O2) Sensor: While primarily used for closed-loop fuel control at higher engine speeds, a faulty O2 sensor can still contribute to poor idle performance, especially if it's providing consistently inaccurate data.
Important Note: Diagnosing the exact faulty sensor requires proper diagnostic tools and procedures. Simply replacing sensors based on suspicion is not efficient or cost-effective. A mechanic should use a scan tool to read diagnostic trouble codes (DTCs) from the engine control module to pinpoint the problem.
