Vehicle speed sensors are part and parcel of modern car technology these days. Every car and motorised vehicle will have one, though some will be more refined than others. Generally speaking the more expensive the car, the more refined the speed sensor. However, this extra refinement can come at a cost. Speed sensors have a habit of going wrong, and when they do they can cause all sorts of problems.
So what does a vehicle's sensor do?
A vehicle's engine sensor or vehicle sensor as it is better known, sends information to a car's computer and tells it how fast the car's engine is spinning at any given moment. The speed sensor does this by recording how fast the crankshaft of a vehicle is spinning. Unfortunately speed sensors are not infallible and do go wrong from time to time.
What sort of problems can faulty engine sensors cause?
A faulty vehicle speed sensor can cause a number of problems. The problem often is that these faults or symptoms can be very difficult to diagnose. Sensor faults can appear similar in many ways to other vehicle faults like a defective coil pack or a bad throttle position sensor. In fact the symptoms can often be identical. That's why it's probably always best to consult an expert. However, there are certain common symptoms that generally can be solely attributed or associated with a bad engine sensor:
Transmission revs higher before it changes gears
The car's transmission engages into overdrive late and sometimes will never go into that top gear
Brakes are sometimes harder than normal when coasting
Speedometer behaves erratically or sometimes does not work at all
The check engine light comes on intermittently and sporadically when accelerating
The overdrive on/off light blinks on and on for no apparent reason
How to test the robustness of a vehicle speed sensor
If a car is experiencing any of the above symptoms, it is always best if you take your car into a local garage and ask them to run computer diagnostic tests on the vehicle to see if the speed sensor is functioning correctly. Common faults can often be incorrectly diagnosed as major problems when in fact they are just minor issues. Though some of the problems may seem to be transmission-related, it is generally better to take the vehicle to a garage that has complete computer diagnostic equipment before going to a specialty repair shop and carrying out unnecessary expensive repair work.