Hello
Had to change front pipe on NA sw20 1996.
Previous owner or someone else had push connectors on the o2 sensor.
Of course I wasn't paying and in a rush didn't note the order.
On the loom side I have: black, orange, red/white stripe and yellow/brown
On sensor side: black, blue and 2 whites.

Anyone hazard a guess?
Getting car ready for mot and don't want to throw any warning lights on the dash.

Also when changing the front pipe I had a look at the back box and cat. Turns out the inside of the cat has been removed. Reading here and other forums seems the o2 sensor kicks in at a certain heat and with the cats inside cut out it might nit reach the correct temp. Doesn't sound accurate to me. Anyone on here have an opinion?

We all know this is the best forum anyways!

As far as I can tell from the wiring diagrams, on the loom side the heater circuit is
red/white = from ecu
black/yellow = B+

The signal is
black = to ecu
brown = B- (earth)

The sensor I think is a bosch replacement
The 2 whites are the heater, polarity doesn't matter
Black is the signal to the ecu
Blue is earth (B-)

Sorry for not replying but an update of what I ended up doing.

Car was running weird when cold, it seemed to have a high idle and was cherpy/burblin. There was no engine management light on. I checked spark plugs, filters and fresh fuel and those all seemed fine so the only other semi dodgy thing was this sensor wiring so decided to chnage it.

Got a mk3 loom plug from j-spec and a denso sensor from mr2 ben, jointed the loom side with spades rather than bullets and the plugs fit. After plugging it in car running sweet as a nut. Not sure if it was the bullet connectors, the wires were connected wrong before (I don't mind now what way they were) or if it was indeed a bad sensor.

Mr2 Ben fella on the phone did say they only recommend denso sensors as they have heard other people having weird issues with other brands. My local motor factor could have got me a non denso sensor and i wasn't sure if mr2 ben was just giving me a sales pitch but went with his sensor and seems he was 100%.
Fella was very helpful on the phone about a few other things, won't be doubting them again!

The mk3 loom plug wiring is different colours to mk2 colouring but only off by one wire so wasn't hard to work out. Picture below if anyone is interested in the future for reference.

Thanks for the update, could you list the wire colour match i.e which colour on the original loom matches the Denso sensor colour ?