One problem related to engine knocking noise has been reported for the 2012 Ford Focus. The most recently reported issues are listed below. Please also check out the statistics and reliability analysis of the 2012 Ford Focus based on all problems reported for the 2012 Focus.
I got into my car after work and noticed the check engine light on, as I left the parking lot of my job and headed towards the freeway which is across the street, my car would not accelerate . I could only reach speeds of 40 mph and the car began to shake and I could hear knocking sounds coming from the engine. I exited the freeway and took streets home, after about 30 minutes the shaking stopped and I was able to pick up speed but the engine light remained on. The very next day there was no engine light on and the car ran smoothly but on the third day as I got in my car once again the engine light was on, and as soon as I pulled out of my driveway, the car started shaking and this time I could only get the car to reach 20 mph which was once again accompanied by loud rattling and knocking coming from the engine. The engine sounds like it trying to accelerate but the car just doesn't pick up speed.