The Ford Focus is a popular passenger sedan. It was introduced to the driving public in the 1999 model year and remains in production as of 2011. Some owners of early Focus models have experienced problems with the power train control module.
A power train control module (PCM) is a computer that regulates the emissions, fuel injection and the spark ignition of the engine. The Service Engine Soon" warning light illuminates whenever a fault is detected by the PCM. The fault is assigned a code and stored in the PCM. All contemporary passenger cars have this on-board computer.
2009 Service Bulletin
In August of 2000, Ford issued a technical service bulletin warning of a PCM problem in some of the 2000 Focus models. A defect in the PCM causes the engine not to start after it is cranked. This problem was limited to Focus models equipped with an automatic transmission.
Calibration of the PCM can affect throttle response. If the PCM is out of calibration, one of the obvious signs is that the engine surges when the accelerator is released. If the diagnostics cannot pinpoint the condition, the PCM may be reprogrammed to the latest calibration.