P0135/P0136, I HAVE searched, honest!!
 

I bought my college-kid daughter a 99 S70 last year. Beautiful, great car. She (and I) love it, and have put about 30K miles on it since I drove it home from NJ. The check engine light came on last month, P0135. I changed the front O2 sensor and turned the light off, but it came back on after a few minutes. P0136 this time, so I changed the back sensor. The light came back on anyway, still P0136. I put plugs in it yesterday, and it runs wonderful, lots of power, but the light still comes on after a few miles. I started it and sprayed starting fluid around in the engine room, but got no evidence of a vacuum leak. Anybody got any insights about this situation?

Also, how do you check the transmission on this? I don't want to tear something up. It's a 5-speed, as she specified. And, yes, I have searched.

Did you use a Bosch O2 sensor?

What do you want to do with the tranny? Just check the fluid?

Both new sensors are Bosch.

I want to check the transmission fluid. Or does it need changed, too, since we've put about 30,000 miles on this car?

There should be a plug about half way up to check it since it is a manual tranny.

You can change it if you want to.

I wonder if the computer needs to reset. Try removing the fuse for the ECU for about 10 minutes then plug it back in and see if they come back.

Clear the codes first then pull the fuse.

Haven't checked the xmsn yet, but the fuse removal thing fixed the CEL. Thanks. That's a load off one's mind, that light not on any more. Makes me wonder what would have happened if I had done that earlier in the process.....

ECU Fuze.
 

I appear to be having the same issue with my o2 sensors and I saw the suggestion about removing the ECU fuze. This may seem like a silly question but where exactly is the Ecu Fuze. I checked the manual for my 99 v70 and can see nothing that identifies a ECU fuze.

Many thanks.