Try disconnecting your red battery cable for an hour, or two, then re-connect it. This works sometimes, IF your engine is fully tuned; air filter, fuel filter, oil change, Transmission Fluid, etc.
The 2003 Ford Focus has an inline 4 engine.
The 2003 Ford Focus has a 2.0 L base engine size.
The engine number of a Ford focus 2003 zx5 is located on the sideways of the engine.
The 2003 Ford Focus's engine produces 130 hp @ 5300 rpm.
The 2003 Ford Focus's engine produces 135 ft-lbs. @ 4500 rpm.
In a 2003 Ford Focus : The engine coolant reservoir is on the passenger side of the engine compartment ( it has a thread on pressure cap )
why 2003 ford focus stall when air conditioner is turned on
The SOHC 2.0 Ford engine is NOT an interference engine
In the oil pan, in the engine.
The AC recharge valve for a 2003 Ford Focus with a Zetec engine is near the firewall. It is the larger of the two lines going to the compressor.
Engine
The check engine light on a 2002 Ford Focus can be reset by disconnecting the battery for 1 to 2 minutes. This resets the vehicle's computer and clears the light.