The 05-07 Focus is one of the models with the highest rated reliability in Consumer Reports. Starting in 05, the Duratec engine became the base engine, and it has a timing chain instead of a timing belt. Chains last much longer than belts. That engine also has coil on plug ignition. Brakes were also improved for 05+ Focis.
There are some drawbacks you should be aware of. The automatic transmission was not changed, and the AT was never super reliable. Most of the problems come from either owner neglect, or solenoid failures. The solenoid failures are not expensive for a DIYer to repair, but are very expensive if you take the vehicle to a shop. Many people end up getting a whole new transmission when just a single solenoid replacement is needed.
The MT is more reliable, but the clutches for these cars are more expensive in parts to replace due to a dual mass flywheel. This must be replaced with each clutch adding $3-400 in parts to the job. Shops that fail to replace the DMF or flywheel bolts should not be consulted for repairs- unless you like having the engine and transmission taken apart a second time in 6 months. The shift tower pin tends to go out around 150k depending on how the driver treats the car. We have a How-To on this, but most people would take the car to a shop instead of spending 4 hours and $1 in parts to repair it. Earlier models can have this same issue, so it is not a 05-07 problem. Some less harshly shifted models might never experience this issue.
There are some common engine issues. The most common is a sound that sounds like bad valve adjustment to even the most trained ears. It is not valves, and that can be diagnosed simply by using a stethoscope or probe to listen to the valve cover. The sound comes from the intake manifold. Ford installed flaps, called tumble flaps, in the intake manifold to meter air velocity and flow with rpm. Over time these flaps wear out, and flop around inside the intake making a sound like bad valves. Mine have been making the sound since 90k miles, and I now have 150k. It's more annoying that people think your car is about to explode. To repair it, you must replace the intake manifold, or remove the tumble flaps. We have How-To articles about how to remove the TFs, but a loss of low end power will be felt as a result. New intake manifolds cost $2-300, and used manifolds are about $100. Eventually I'll write a How-To on this when I get around to changing mine.
OH, 05 model year vehicles have a really annoying starting issue. Every few times you go to crank the engine, it will take 10 seconds of cranking to start, or you will have to stop cranking, and crank a second time to start the engine. I've been dealing with that since I bought the car. What I do is crank the engine for about 1 sec, if it doesn't start, then I stop and crank again for 1 sec. It always starts immediately on the second crank. It's just an annoying issue that makes people look at you funny when it happens.
You might read about ignition lock cylinder issues with these cars. The improved ignition lock cylinder design of 05 does not have this problem. That is the lock cylinder we tell everyone to change the old style cylinders to- only 00-04 Focis have lock cylinder issues.
Another common issue is an easy repair. During the winter months the throttle might become hard to press. This problem can be easily remedied by removing the air intake, and cleaning the TB and throttle plate with a rag and some carb cleaner. Another "problem" is the lifetime air filter which was only used on the 05-07 Focis. The filter is located in front of the driver's wheel in the fender, and if road debris damages the filter it can cause stalling and engine running problems. The filter is very expensive to replace- $2-300, but aftermarket cone filters are available. You can even make one yourself for about $30- the "Stealth Air Intake". I used one of those for 4 years.
All cars have issues over age. We know the Ford issues, but not the Civic or Mazda3 issues.
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