i have a 1998 v5 impretza turbo,does anyone know which colour is the signal wire on the o2 sensor as i have a air/fuel ratio guage i need to fit

any help will be very much appreciated

 

It should have two wires that are the same colour (white from memory) and a single colour one (black from memory). It's the single coloured one that is the signal wire. The other two are the +ve and -ve for the heater...

 

If unsure, stick a multimeter's red +ve probe (black -ve earthed on inlet manifold) up each one's entry to the connector.

With a fully warmed, idling engine you should see the voltage continuously cycling up and down between 0 and 0.9V (if working properly). When you see this, that's the signal wire.

 

It's as joz says it is the single black wire with the gold coloured pin on the plug , the two white wires have silver connectors on the plugs.

 

Monza, the other two are right about the colours of the wires on the sensor itself but you'd be a bit silly wiring an A/F gauge in on the engine bay side of the loom.

Far easier to tap into the other end of the cable as it enters the ECU - that way you can take advantage of the fact that Subaru have already got it into the cabin for you.

Lift the front passenger footwell carpet and remove the cover plate and you'll see the ECU. The O2 sensor signal runs into connector B136 (the blue plug).

The pin numbering runs from right to left, top to bottom as you look at the back of the plug. So, the top right pin (pink/blue wire) is number 1, top left (yellow/blue) is pin 9. Pin 21 is third row down, three in from the right. Should be a white wire.