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Is there a sensor that would cause the engine to shut off on Geo Metro?

Yes, several sensors on a Geo Metro (and most cars) can cause the engine to shut off, either directly or indirectly. Here are a few key culprits:

* Crankshaft Position Sensor (CKP): This sensor tells the engine control module (ECM) where the crankshaft is in its rotation. If it fails, the ECM won't know when to fire the spark plugs, leading to a no-start or stalling condition.

* Camshaft Position Sensor (CMP): Similar to the CKP, but for the camshaft. A faulty CMP will disrupt the timing of the valves, causing the engine to misfire and potentially shut down.

* Mass Airflow Sensor (MAF): This sensor measures the amount of air entering the engine. A faulty MAF sensor can cause the engine to run lean (too much air, not enough fuel) or rich (too much fuel, not enough air), leading to stalling or a complete shutdown.

* Throttle Position Sensor (TPS): This sensor tells the ECM the position of the throttle plate. A faulty TPS can cause erratic idling, stalling, and even prevent the engine from starting.

* Oxygen Sensor (O2): While not directly causing an immediate shutdown like the others, a faulty O2 sensor can cause the engine to run poorly and eventually stall, especially if it's causing a very rich or lean condition.

* Engine Coolant Temperature Sensor (ECT): This sensor monitors the engine's temperature. A faulty ECT can cause the engine to run too rich or lean, potentially leading to stalling.

* Vehicle Speed Sensor (VSS): While not directly linked to engine shutdown in the same way as the others, a faulty VSS can prevent the engine from starting or cause stalling, especially on automatic transmissions, due to its role in transmission control.

It's important to note that a malfunctioning sensor doesn't always result in an immediate engine shutdown. Often, you'll see symptoms like rough idling, stalling under load, or poor fuel economy before a complete failure. A diagnostic scan tool (OBD-II scanner) is the best way to pinpoint the exact sensor causing the problem.