I have found that with most sensors in general if you take them out and wipe them with a clean rag or spray them with a sensor safe cleaner it helps them function better and expands their life, this is especially true with sensors that rely on any type of magnetic feedback like the CPS, over time the magnetic field gets interrupted by metallic particles and reduces the sensitivity of the sensor. Also a great idea to clean off all of your magnetic drain plugs so that the metallic particles do not get stuck to the sensors instead, if the magnet is covered with enough shavings and gunk it cannot do its job, it doesn't take much electrical current to turn a sensor into a magnetic field and attract the particles that would otherwise be sticking to the magnetic drain plug. I hope that all made sense anyway.