Determine camshaft and crackshaft position and sends this information to the ECU. The computer uses this and other inputs to calculate injector on time and ignition system timing.

What they do

Sense and signal the ECU, changes in atmostpheric pressure and / or engine vacuum so the computer can control the fuel and ignition operation for varying

What they do

Measure the fuel temperature at the rail thus determining the density of the fuel.

What they do

Measure engine coolant temperature and signals the ECU to adjust the fuel mixture.