Guys, new to the forum and a new problem, which I haven't found a full answer for yet.

So we have a 2.0GX NA Impreza, 2007 Hawkeye, only 45000 miles, but with an aftermarket exhaust fitted. The Exhaust has no CAT, which we'll be dealing with in due course, but for now it has got both upstream and downstream O2 sensors fitted, original Subaru parts, fitted by the last owner, the downstream one being fooled by one of those mini-cats. So for the last couple of months all good, but lately a bit of hesitation when accelerating and now it's thrown a P0133 trouble code (slow responding upstream sensor).

Now checking the wiring diagram it looks like I should have a 6 way black plug for the upstream sensor and a 4 way grey plug for the downstream. However these look like they're flipped on our car. So this would seem a simple fix, but the wiring colours I have are entirely different on the harness side, from what the workshop manual says. See picture attached.

The 4 way has Red, White, Pink and Black, but the diagram says it should be Black, Black/White, Black and Blue/White.

The 6 way has Yellow, Green/Black, Green and White/Blue, but the diagram says it should be Black, White, White, Red!

So does anyone have a non-turbo 2.0 Hawkeye and could they check the wiring colours on their harness to see if there are any yellow or green wires on theirs, and if so, does the black 6 way go upstream of the catalyst?

In the meantime if the weather's good, I may jjust attempt to swap them over on the exhaust and see how it performs after that.

I would go for the exhaust swop first - easy move, keep us posted