On your 2000 Toyota Echo the engine started reving when stopped at a light It ran normally driving you did run very low on gas this morningthe warning flasher to go off?

The high idle at a stop light on your 2000 Toyota Echo, coupled with recently running very low on gas, strongly suggests a problem related to fuel delivery. The low fuel level might have introduced air into the fuel system. When the engine is idling, the fuel pump may struggle to maintain sufficient pressure, leading to erratic idling and higher RPMs to compensate.

However, it's crucial to rule out other possibilities before jumping to conclusions:

* IAC Valve (Idle Air Control Valve): This valve regulates idle speed. A dirty or malfunctioning IAC valve is a common cause of high idle.

* Throttle Position Sensor (TPS): A faulty TPS can send incorrect signals to the engine computer, causing erratic idling.

* Mass Airflow Sensor (MAF): A dirty or faulty MAF sensor can also lead to idling problems.

* Vacuum Leaks: A leak in the vacuum system can disrupt the engine's idle.

While the low fuel situation is suspicious, it's important to have a mechanic diagnose the problem properly. They can check fuel pressure, inspect the IAC valve, TPS, MAF sensor, and the vacuum system to determine the exact cause. Simply filling up the tank might resolve the issue if it was indeed air in the fuel lines, but it won't fix underlying problems with other components. Ignoring it could lead to further engine damage.