Oxygen sensor questions?

What would be symptoms of a failing o2 sensor?

 

Car seems to randomly lose power, almost stall, or stall, tach jumping around a bit searching, starts right away again after stalls, but will either run ok again/or like crap... Seams ok when engine is cold, but after warm up and driving for a while it will happen, often just when idleing at a light or something.

 

Ive changed the knock sensor and cleaned up the MAF and idle air control valve...

 

Now im thinkin could be o2?

Not throwing a code currently..

 

Any help would be greatly appreciated,

Thanks guys

Hello;

With the flickering tach, I would be looking at the electrical connections. Another area would be the ignition switch and ignition, fuel pump relays. These are located above the interior fuse box, Steven.

Hi,

ON the 1st Gen cars the O2 sensor doesn't do as much. If car is stalling/dying I'd replace the MAF (it may not set a CODE/cause the CEL to come on even if bad and cleaning won't fix it)...easy if your car is a '92+ as they all used the Green Label/plastic JECS/AUTECS MAFs, which are the same for ALL Subaru Legacy/Outback/GT/Forester/Impreza from thru '98 (some '99). If yours is the silver/metal from the '90-91 years, less common.

 

Hit up your local PullandSave or other wrecking yard - or post on here or Legacy Central and you should be able to get one for less than $40. If bought @ a yard you can usually return it if it doesn't fix the issue.

 

Td

My 93 had the silver MAF when I got it. The MAF was bad and it took me months to track down the problem and replaced it. I had hesitation problems and sputtering. It did force me to work everything over though. Fixed every boost leak (there were a lot), replaced the injectors, replaced the fuel pump with a Walbro, etc... It was maddening. When I replaced the MAF the car finally drove like I thought it should.