ive got a 4 wire sensor,2 are heater,black is signal +,grey signal -,does it earth or get live from the mega unit?

sorry read wrong

[Edited on 11-12-06 by davrus]

the lambda works like a battery, and gives out 0 to 1 volt,

connect the signal - to earth, and the signal +to the megasquirt.

use screened cable for the signal + and earth the screen at one end.

hth

Ray

cheers ray