Ok I know this is very difficult to diagnose, but give me your best guess. My check engine light has started to come on. It will eventually go off, but sometimes comes back on when I start my 00 OBW. Engine seems to run fine. Today when I was stopped at a light the RPMS dropped for a second, but then went back to normal. This happened at a few other lights.Today was the first time that I noticed that. I have no idea what the problem is. Could it be an oxygen sensor, PC valve, or EGR valve? Any other ideas? Thanks!

go to autozone, have them read the code

mileage would help too. If its over 100K a blind guess would be an O2 sensor, but have autozone pull the codes.

 

 

nipper

I went to autozone for a previous CEL and the guy told me that he didn't think they could pull the codes on Subarus. Is that true? It sounded kinda bogus to me, but I don' know. He said if he plugged it in the airbag might go off.

If its newer then 1995 yes he can, older no he cant

 

nipper

Tell the 'autozoner' to humor you and give it a try. The '00obw is ODBII so and ODBII reader will read the codes. That's pretty much the whole point of ODBII - to have the same standard for all vehicles sold in the U.S.

 

I don't know about his thing about the 'airbags might go off'. There are some ~'96's I think that sometimes have an issue with airbag deployment for no apparent reason so maybe that's what they're thinking of.

 

If it is front O2 sensor, note there was a recall for some '00obws on this sensor (for cracking), and get an OEM sensor for the front.

 

Autozone not wanting to read the codes reminds of when I went to Carquest looking for a code reader. They told me it was illegal to sell them anymore. Went down the road to Pepboys and they had many models.

I went to autozone for a previous CEL and the guy told me that he didn't think they could pull the codes on Subarus. Is that true? It sounded kinda bogus to me, but I don' know. He said if he plugged it in the airbag might go off.

 

Sounds like the mgmt at that store needs to know what thier employees are saying. The idea behind the free code reading is to sell you parts.

 

nipper

Have this same problem with my 02 Legacy wagon. It has been going on for about 5 months. I have had it diagnosed and cleared a few times as being the catylitic converter. Performance has been fine except for a few as you mentioned, drops in rpms at stops. My mechanic told me to hold out for as long as I can given the cost of a replacemtn cat.

Have this same problem with my 02 Legacy wagon. It has been going on for about 5 months. I have had it diagnosed and cleared a few times as being the catylitic converter. Performance has been fine except for a few as you mentioned, drops in rpms at stops. My mechanic told me to hold out for as long as I can given the cost of a replacemtn cat.

 

SIgh...

 

Its NOT your converter. You need a new O2 sensor. When the front O2 sensor goes bad it gives a poor cat effeciency code. It 99% of the time a bad front O2 sensor. This is the heart of your emissions system and will affect drivability, emissions, gas mileage, or all of tyhe above (and sometimes none). Its covered very well in the forums.

If your cat doesnt smell, doesnt rattle when you hit it with your hand, and no high rpm driving issues, then its not your cat.

You need a new mechanic too.

A new cat costs several hundred dollars. A new O2 sensor costs maybe 150. Considering that a high percentage of the "Cat failure codes" are due to a dying O2 sensor (not to mention that the new O2 sensor can be moved to the new cat if it fails to solve the problem) My highest recomendation is to replace the O2 sensor first. Call it a diagnostic, if you want. . .

A new cat costs several hundred dollars. A new O2 sensor costs maybe 150. Considering that a high percentage of the "Cat failure codes" are due to a dying O2 sensor (not to mention that the new O2 sensor can be moved to the new cat if it fails to solve the problem) My highest recomendation is to replace the O2 sensor first. Call it a diagnostic, if you want. . .

 

Actually if your going the o2 sensor doesnt solve the problem, and the cat is shot (if its high mileage), no money lost. I would bet that the o2 sensor isnt all that far behind the cat and needs replacement anyway.

 

 

nipper

I had an o2 sensor replaced under recall. A week later the check engine light came on. No loss in performance. I find it happens if the gas cap isn't on tight enough, and don't 'top off' the tank when you fill up. Learned to live with the light on occasionally. Just my experience, your mileage may vary.