I had a mechanic work on my car due to Check engine light coming on. He was able to retrieve error code PO136. He said it was Oxygen sensor bank one sensor 2. He said he changed it but the error code did not go away. He also changed the front sensor. He explained that I had to take it to a dealer because he was not able to go any further. He mentioned that Dealerships have a better diagnostic tool that will be able to tell them more. Anybody have any ideas of what it might be? Thanks for your help

Autoenginuity sells a pretty good OBD II reader that works with a laptop computer. On the Oxygen centers, it graphically shows the maximum and minimum voltages generated by the oxygen sensor as the engine runs and will tell you if it is out of spec. You can also retrieve the OBD II codes and clear them. Nice setup for about $180. You can find the ones that only display the codes and lets you erase the codes for $40 (Harbor Freight model)-$110 (Actron).

clear all the codes, disconnect battery for $15 min and see if the code returns
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'88 240, '92 745, '98 v70 John, Tampa Bay

If the 15 min battery disconnect doesn't work, you may try to find out the specific sensor your mechanic installed. I just went thru a royal O2 sensor fiasco with a 96 850. "Generic" sensors are generally a no no. It needs to be Bosch and the right one for your engine. I found out (after more $$$ wasted than I want to admit) that a lot of sensor charts that mechanics and web sites selling sensors use list the wrong # for the 850. I got one from an on line sensor vendor, installed it and reset the code. The car contiuued to run rich and set codes. I took it to my regular mechanic who swapped sensors again ( now I'm in $300.+). Seemed fine for a week and again began to set codes and run like crap. I figured it couldn't be the sensor so I looked everywhere else and I imagine destroyed my cat in the two weeks I screwed with it. Took it to the mechanic of the guy I bought it from (shoulda done that first) and he found the wrong sensor installed. He showed me his updated chart that listed a different sensor entirely. He installed that one (even more $$$) and it's perfect. Back to 25 mpg. Live and learn. As the saying goes, "learn from other peoples mistakes...you won't live long enough to make them all yourself".

bl