I have searched the exhaust pipe and the front of the cat and no O2 sensor! The ECS light is on and O2 sensor is one of the codes displayed, but it just does not seem to exist! I was also told by a mechanic that specializes in Subaru that the ECS in 84s was wildly inaccurate and that if the car runs well chances are there is no fault in the O2 sensor. The car does run well but the miles per gallon is not what I think it should be.....?

 

Also the other code displayed is the coolant monitoring thing. He said if that was truly malfunctioning the car would also run badly. I do suspect something is amiss though because the fan failed to ever come on til I wired it to power so that its on full time with the engine. Also the temp gauge reads almost non existant (the needle stays almost at the bottom of the range even when fully warm). So whats the deal? do I need to replace these items? If so are they not both cheap and easy fixes? If I could find them it might be lots easier but unfortunately Haynes didnt think putting the locations in their manual was necessary.....Thanks in advance.

I believe that the O2 sensor should be on the top of the first cat...hold on ill go out and double check on my car. If its not there that could be your problem. I would look for wiring around that area that just ends. It could be that some dumb a$$ in the past just put on an aftermarket cat that didn't have the O2 sensor mount. As for your coolant fan not coming on it is almost always the fan switch. This is a mercury filled switch that is mounted on the pasenger side of the radiator about halfway down. When goes bad the fan fails to turn on. Since you already told me that the fan motor itself is working, I can say with reasonable certainty that the switch is your problem. Hold on though im going out to double check on that O2 sensor.

 

A few minutes later...Yep its on the top of the cat closest to the engine...or at least it's supposed to be :-)

Bingo! There is no O2 sensor..... :| So what the hell? It does run fine but am I getting lousy mileages as a reult? I suppose if I ever end up having to do an emissions test I am screwed too?

 

And about the coolant sensor.....Is it normal to read at the very bottom of the scale on the temp gauge or could that use replaced and is it cheap?

 

How could I go about rigging an O2 sensor without buying a cat or drilling mine and ruining it? Or can I fix this at all cheaply?

you can drill a hole in the exhaust manifold right before the Cat and buy a threaded plug from an exhaust shop to weld on. Is the wire or connector for the O2 sensor dangling anywhere near by?

I do suspect something is amiss though because the fan failed to ever come on til I wired it to power so that its on full time with the engine. Also the temp gauge reads almost non existant (the needle stays almost at the bottom of the range even when fully warm).

 

The reason your car is running too cool now is that you have the fan hard-wired to be on all the time. These cars don't need a fan on all the time (except I think that the turbo models have a clutch fan as well as the electric fan). You can either put the fan on a switch so you can choose when to turn it on, or replace the thermoswitch in the radiator and wire it back to original.

there is no o2 sensor because the y pipe has been replaced with one from a non-cali hitachi setup