One problem related to gas recirculation valve (egr valve) has been reported for the 2003 Ford Focus. The most recently reported issues are listed below. Please also check out the statistics and reliability analysis of the 2003 Ford Focus based on all problems reported for the 2003 Focus.
Safety hazard-- upper motor mount on 2003 Ford Focus malfunctions/ disintegrates within three months of installation; whether by garage, dealer, or owner. In seventeen months, I have had to replace the mount (when caught) four times and found it again needs replacement. The oem parts say guaranteed but it constantly cost to remove, repackage, ship, and then replace.