Mitsubishi Repair Problems? Ask a Mechanic for Answers ASAP
Hi,First and foremost, don't get used speed sensors. These sensors are extremely common to fail, to the point that there is most literally nothing else that causes the speed sensor faults to come up other than the sensors failing. To get a used one is almost a guarantee that you will get a bad one. They fail that much.
That being said.... C1015 and C100A are for the right front sensor, C102A, C102B and C1027 are for the left rear sensor. Only C1020 is for the right rear you replaced.
So if the C1020 went away after you replaced the one sensor (but of course the others remained), then at least that sensor ended up OK. If it returned as well, as long as there is nothing unusual about the situation (like the vehicle was in a bad accident and could have other wiring damage that was not repaired etc), then you just need to replace three sensors.The U code is most likely not of any interest to us. U14xx faults are usually ABS calibration/coding issues, and if you put a used unit in there that would cause that code in itself.