One problem related to engine clicking and tapping noises has been reported for the 2002 Ford Focus. The most recently reported issues are listed below. Please also check out the statistics and reliability analysis of the 2002 Ford Focus based on all problems reported for the 2002 Focus.
Vehicle failed to start after completing a 30 minute drive and being turned off for about 5 minutes. Clicking noises like starter failing to engage or low battery ensued. When hood was lifted and battery cover removed and cables and connections were inspected, it was observed that the positive cable off the back of the positive battery harness was exposed, the insulation being almost completely melted. The exposed wires showed signs of fraying and burning. After attempting to jump start the vehicle about 3 times and waiting about 20 minutes, the vehicle started. The vehicle was driven about 20 miles to a service station and inspected by their mechanics. It was decided for safety reasons(fire hazard) to leave vehicle. In 45 years I have never known a battery cable to melt even though I have had bad connections, corroded terminals and harness to the battery and even bad starters. All of the above reasons were the only solutions offered to me.