astro oxygen sensor wire colors

my 2003 astrovan has O2 sensors with two black wires and a purple and a white.
I have 3 replacements, AFS123 that have 2 browns, and a thicker light brown and a thicker purple wire.

Does anyone know how these hook up? I have no instructions

Welcome Aboard!

It sounds like you have one of the "universal" replacement sensors. The two brown wires should be for the sensor heater element. The purple should be the sensor signal, and the tan would be the sensor ground.

http://72.19.213.157/files/4WireHO2S.gif

The original sensors likely used the two blacks (or a black and black/pink) for the sensor heater element, the purple for the sensor signal, and white for the sensor ground.

Thanks for the reply. The diagram is great.