Any OBDII Gurus Out There?

[indyzmike]

My 2000 Subaru is being a pain. I have a Check Engine Light(CEL) with a code for bad catalytic converter. I went to the dealer(Sommers) and they wrote it up for $1,600 to replace the converters and oxy sensors. I declined. Bye bye $100

I went to Napa and bought two Bosch oxy sensors and installed them, cleared the code, and drove the car. CEL came back on with the same code. I go back to NAPA and bought new catalytic converters and installed them. I cleared the code and drove the car. CEL light came back on.

I figured the chance of a new converter set being bad was slim, so I took the car to the dealer(Jakobs) to verify that the computer was seeing the oxygen sensors ok, and that the sensors were working. They said all was fine and cleared the code. They wrote it up for $1,300 to replace the converters and oxy sensors. They would not troubleshoot it any further because it had aftermarket parts on it. Bye bye another $100.

I ordered the cable to connect my laptop to the car to monitor the sensors. The sensors seem to be working fine but I am not positive. I want to try different software that might be easier to interpret.

Before all of this started, the exhaust heat shields were clanging around, so I removed them. Would the reduced heat in the converters make that much difference? Thanks, Mike

[wikked]

Are the Bosch oxygen sensors stock on those?
I had an oxygen sensor related CEL once on my Talon, and tried buying a non-oem sensor ($40), instead of the oem ($110)... CEL only went away after I bit the bullet and bought the Mitsu OEM. :|

[Car Guy]

The heat shields shouldn't have anything to do with the converter's operation; they're more for keeping heat at a minimum from the areas near them.....


Just a few ?'s for ya..........

Do you know exactly what the codes were when you took it to Sommers...???

After you replaced the O2's were the codes the same, and if not do you know what they were...???

Same goes for when you replaced the converter; were the codes the same, and if not do you know what they were...???

Last one; was the converter from NAPA an OEM in size, fit, and function...??? Many aftermarket converters can give you issues because the manufacturers cheap out on the material that actually does the work......



Are the Bosch oxygen sensors stock on those?
I had an oxygen sensor related CEL once on my Talon, and tried buying a non-oem sensor ($40), instead of the oem ($110)... CEL only went away after I bit the bullet and bought the Mitsu OEM. :|

This ^^^ might very well be a possibility too.....:headbang







:3gears::3gears::3gears:

[Bart H]

Get a mil defeat to move the 2nd o2 sensor after the cat out of the exhaust stream.
Visit Nasioc.com for all your subaru needs.

[indyzmike]

Thanks for the help!!! Code is a P0420. It has not changed. The converters from NAPA are a direct replacement($350). Either the MIL defeat or an OEM sensor might be my next move.

[BAD LS1]

Yeah if u swaped the sensors out, and its still throwing the 420, the cat is fubared. It will probaly bust apart and clog the exhaust in the future...

You can get simulators to plug in that gives the mid 400 mv reading the computer it wants to see to keep the light off.

May as well get your self a an off road down pipe, and the sim right away. Enjoy free flowing exhaust and will still pass a plug in test!

[70challenger]

i deal with alot of thease at work and i knew even before u posted the code that it was a p0420. i have seen this before many times where i offer the customer the oem cats for the outragous prices that the dealers/oe's charge OR say a walker brand cat with a little time to chop the old one out and weld the new one in. i've had a few cars come back with the same code a few weeks later. the jist of the story is the computer is use to or suppose to reconize certain changes in waivform between the front and the rear o2's. it the waivform is to close or sometimes if it doesnt store certain gases (mainly oxygen) then it trips the code. if you can watch waivforms on ur laptop, the front 02 should go between 100-900mv like crazy. the rear will seem to move alot slower compared to this.

sorry for the lenthy post, just trying to help out.

[indyzmike]

The front sensor is very active from .1 to .9 . The rear sensor does not give a good reading. It has some action, but not much at at all. If I am on the freeway and coasting, the voltage goes way high until the RPM drops off . It is hard to read in the software that I have so I am going to try different software.

[Poncho]

bad REAR o2s?

[Car Guy]

The front sensor is very active from .1 to .9 . The rear sensor does not give a good reading. It has some action, but not much at at all. If I am on the freeway and coasting, the voltage goes way high until the RPM drops off . It is hard to read in the software that I have so I am going to try different software.

What exactly do you mean by "hard to read"...???







:3gears::3gears::3gears:

[indyzmike]

The graph is so darn small I can't see it while driving.

I bought a sensor from the dealer today. Hope that does it.

[BAD LS1]

Yeah the rear 02 doesnt swing like the front does... the front wil be constantly moving due to the constant shift from lean/rich. mid .400's is normal on the post cat to see with a function cat. However that sensor is seeing something diff than its programed to like, and after 2 times of that, it kicks the light... dont waste anymore time, ORDP and 02 sim. Solved.