I got a P0175 code(too rich). I found a vacuum line off. Reconnected, runs great! Only problem is that I am getting P0131 and P0137 codes now. I changed the rear O2 sensor about a month before I found the vacuum leak. I replaced it with a spliced universal instead of one with the connector. The splice looks good. The only thing I can think of is that the tape is melting into the butt connectors and causing the problem(the splice is right next to the cat).

 

Those sensors are really not meant to be spliced.
They really don't like it.

But double check all the splices.

 

I cant imagine that the circuit could be that sensitive to a splice, but this is my first Volvo. I have always spliced O2s the same way. The only difference here is the location of the splice. If I have to go to one with the connector it will be about $200 versus the the $50 I spent on this one. It is made by KEM a brand I have always used. Maybe the difference is GM versus Volvo, I don't know. Is there a common ground to the 2 sensors that could be causing the problem?

 

Most of the newer cars 1995 and newer the o2 sensors breath through the sensor wires. The have air that runs through the middle thats why they don't like to be spliced.

These cars usually don't have a wiring issue. The sensors go bad.

Does your scanner allow you to monitor the sensors?

 

I can't monitor the voltages through the scanner. It is the cheap $70 one that will let you see the codes and clear them. I just hate to pay $200 for one after just paying $50 for the other one. Any line on a cheaper one?

 

In the General section I made a post with links to sites. Check some of them out.
Other members have added some as well.
If you want to try to read with a meter here is a link for a wiring diagram.
http://www.volvotechinfo.com/WD123/

 

Ok. So I respliced the #2 O2 sensor, no change. I pulled it out and let it dangle, viola no codes. I let it run about 10 minutes and still no codes. I cleaned it and put it back in and it kicked out P0131. I let it run a little longer and then I got both of them again. Huh?? Is it possible this new sensor grounding both of them out or what?[sm=dontgetit.gif]

 

Also, contrary to what I have read here and elsewhere, it is easier to change O2 sensors with the engine hot. I disconnect the sensor connectors and let the car warm up. That way the exhaust is hot and the sensor is cold, it doesn't take any effort to remove them that way. Also Tech I like your signature. My motto is "I help where I can, I don't where I can't."

 

LOL It could be doing it.
Try to find even a used OEM and see if it make a difference.

 

Well, I replaced the rear O2 with an OEM Bosch with the connector. No codes for 30 minutes idling. I will check it with the scanner after I drive to work tomorrow. By the way, I found the sensor on eeuroparts.com for $175 with free UPS ground shipping. I printed it out and took it to Advance and they honored the price. I ended paying $12 more that way, but at least I could get it overnight. As a side note-could they put a few more wire clamps on the darn thing[sm=shootshoot.gif].

 

That seems to have done it. Two weeks and still no codes. Who knew (except Tech). Just did an oil change with 1 quart Lucas and 5 quarts 10w-40 and it seems to have helped my valve cover gasket leak. I haven't checked the oil pump leak yet, but cross your fingers. Even with the Lucas it only cost me $25 to do my oil change. That is still cheaper than most oil change places around here unless you get the $15 special. Then you never know what you are getting. Thanks again Tech for all your help.

 

No problem glad to help.