I just bought my 97 LX 3 weeks ago with 120K on it. after 2 days it threw a CEL. comes back as P0420 upper o2 sensor. i had advance get me a new one. it looked different but the old was a NTK and new was a bosch. Get it installed and plugged in and within 5 feet i get another CEL. comes back as P1195. cleared code and it came back right away. pulled out new sensor and put back old one. code came on right away P1195. drove back to advanced and cleared the code. then drove 10 miles home and now code. it normalld took about 20-30 miles for the CEL with the o2 sensor to come on. they are getting me a new one. any ideas?

 

Thats an EGR boost sensor code. It could be a clogged hose to throttlebody/poor electrical connection/dirty egr ports or bad boost sensor. Definitely not an o2 sensor code.
I would clean the throttlebody and egr really well first.

 

Is it normal for one code to be hiding another code? once i put the old o2 sensor back in it the EGR code went away.

 

usually, you pull two or three codes at a time. if they only found one, they didn't look hard enough. the sensors that they use generally require you to push a button to get the second code and they just don't seem to have the time for that.

this sounds like the infamous protege egr issue. it has always been a weak point on the motor.

 

Car up to hill was making detonation /pinging/ . After EGR cleaning car just fine. Tube from Manifold to EGR was clogged.

 

Ok here is an update. I changed the O2 sensor. It got rid of that code. then i got the code P1195. EGR valve. i pulled the EGR off and cleaned it. unhooked the batt. and code went away. 2 days later i get a CEL again. i'm sure its the EGR again. any ideas? Plugged vac line? any ideas?

 

did you clean out the EGR tubing as well? you can spray some brake cleaner down it to get everything broken up and then take a toothbrush to clean down in the ends of the pipe.

 

What do you mean by EGr tubing? the solid line going to the exhaust manifold. no i didn't clean that out.

 

that's the tubing. it can get clogged and turn rock hard eventually. just spray some brake cleaner through it until it runs clear. might take a couple of bottles.