Oxygen Sensor

[Big Dave]

Does anyone know anything about the oxygen sensor on a 1991 Toyota Hilux Surf 2.4TD? I have checked my engine trouble codes and had 5 flashes on the engine light.
Thought I was very clever to be able to check the codes but I don't know where to start looking for this thing. Do I need to replace it?
I have just done the Turbo "washers" mod, could this have caused the trouble code or could this be an old code that still needs to be cleared?

Thanks in advance!

[dandownunder]

If your engine check lite is coming on now you have done the turbo spacer mod, I'd suggest your overboosting, your washers might be a bit big. do you have a boost gauge. the Surfs computer warns of overboost around 12-14psi.
cheers
Dan.

[Big Dave]

I did'nt do the error code test until after I had done the mod, but I don't think that the error is related.
The engine check light does'nt come on, only when I connect the TE1 and E1 terminals for the error code test!

The Turbo Mod works great and I can add that there is no lag when I put the pedel to the metal.
Yes there is a little Turbo whistle but thats fine.

I've looked on the net and have found that when the oxygen sensor gives up the ghost, the fuel mixture goes for a loop and will run rich however this was in general and not directly related to a Toyota Surf 2.4TD