xrsi

iTrader: (1)

i need urgent help with the wiring of a lamda sensor to run my air fuel ratio gauge...

the sensor has 3 wires...

2 white and one black....

im guessing the black is an earth, but what do the other 2 white ones do?

i take it one is a feed to an ecu or gauge.. but is the other a poss or another feed off?

also does anyone know, on an autometer gauge is the purple the feed from the lamda sensor?

richm

Conventional Lambda sensor wiring colours:
2x whites - heater, connect to ignition switched 12V supply and ground
Black - signal wire to gauge

on a 3-wire sensor the signal ground return is via the body of the sensor, and hence back via exhaust and engine block.
on a 4-wire sensor, the ground return would conventionally be isolated from the sensor body and come out on a grey wire.

xrsi

iTrader: (1)

what does the heater do? is it really needed?

richm

the heater maintains the sensor element at the right temperature for correct operation (around 600 degreesC), with assistance of any exhaust heating that it gets. If the sensor is mounted reasonably close to the engine, the exhaust heat will be sufficient to maintain temperature without the heater, although on idle it ,may well cool down too much to work correctly without heater, and will take a while to warm up from cold..

xrsi

iTrader: (1)

will connect it then!

what sort of current do they need to opperate?

richm

it will be better with the heater connected.
Expect it to draw around 1-2 amps from a 12V supply, dependant on the sensor temperature (takes less current as the sensor heats up)

xrsi

iTrader: (1)

oh not bad at all then! will get onto that in the morn... one less thing needed to do on the car then