The most common culprits in this scenario often relate to things that change behavior as the engine gets hot and under load (higher speeds):
* Oxygen (O2) Sensor: These sensors measure the oxygen content in the exhaust. A faulty one can cause a rich or lean fuel mixture, triggering the light. They're usually located in the exhaust manifold or catalytic converter, and there can be multiple on the system (one before and one after the catalytic converter).
* Mass Airflow (MAF) Sensor: This sensor measures the amount of air entering the engine. A dirty or faulty MAF sensor can lead to an incorrect fuel mixture and trigger the light. It's usually located in the air intake tube, close to the air filter.
* Throttle Position Sensor (TPS): This sensor monitors the throttle plate position. A faulty TPS can cause incorrect fuel delivery and ignition timing, resulting in the light illuminating. It's usually located on the throttle body.
* Crankshaft Position Sensor (CKP) or Camshaft Position Sensor (CMP): These sensors tell the engine's computer where the crankshaft and camshaft are in their rotation. Issues here can cause misfires and trigger the light, especially under load. Their locations vary greatly depending on the engine.
You absolutely need to have the car diagnosed. A mechanic can use an OBD-II scanner to read the trouble codes stored by the car's computer. These codes will pinpoint the likely cause of the problem much more accurately than guesswork. Simply looking for a disconnected wire without knowing the code is inefficient and could lead to wasted time and money.
Do not attempt to fix this without proper diagnosis. Replacing the wrong sensor is a waste of money and may not solve the problem.
