# Concepts: Camshaft vs. Crackshaft Position Sensor? **URL:** \ **Category:** General Discussion\ **Created:** [April 22, 2012, 12:03am UTC](https://community.cartalk.com/t/concepts-camshaft-vs-crackshaft-position-sensor/72042 "2012-04-22T00:03:37Z")\ **Posts on this page:** 3\ **Page:** 1
**Author:** ![UsedEconobox\_2\_UsedBMW](https://avatars.discourse-cdn.com/v4/letter/u/8491ac/32.png) [@UsedEconobox\_2\_UsedBMW](https://community.cartalk.com/u/UsedEconobox_2_UsedBMW)\ **Post date:** [April 22, 2012, 12:03am UTC](https://community.cartalk.com/t/concepts-camshaft-vs-crackshaft-position-sensor/72042/1 "2012-04-22T00:03:37Z")
I am just diving back into cars after many years. Trying to fill in gaps of conceptual knowledge. I understand that these 2 sensors are part of a fuel injection system. It is no longer purely mechanical with lifters, rocker arms, valves, etc. What is the difference between them? I have read they both are used to determine when to fire the spark plug. (Something the timing belt used to do?) Can you share the basic concepts behind these 2 sensor’s roles? ---
**Author:** ![pleasedodgevan2](https://avatars.discourse-cdn.com/v4/letter/p/ad7895/32.png) [@pleasedodgevan2](https://community.cartalk.com/u/pleasedodgevan2)\ **Post date:** [April 23, 2012, 7:15am UTC](https://community.cartalk.com/t/concepts-camshaft-vs-crackshaft-position-sensor/72042/2 "2012-04-23T07:15:52Z")
A crackshaft has a street value which is higher than the cost to manufacture. The police have great leeway when assigning value. ---
**Author:** ![the\_same\_mountainbike](https://avatars.discourse-cdn.com/v4/letter/t/c89c15/32.png) [@the\_same\_mountainbike](https://community.cartalk.com/u/the_same_mountainbike)\ **Post date:** [April 24, 2012, 2:03am UTC](https://community.cartalk.com/t/concepts-camshaft-vs-crackshaft-position-sensor/72042/3 "2012-04-24T02:03:23Z")
Here ya go. This explains it beautifully. [http://www.aa1car.com/library/crank\_sensors.htm](http://www.aa1car.com/library/crank_sensors.htm)