my dodge neons check engine light came on a couple weeks ago, didnt really affect anything except for maybe poor gas mileage (p0038). i went to advance auto and bought 2 o2 sensors, a direct fit downstream(ntk) and a universal upstream(bosch). i got under my vehicle and quickly found out the problem was with the downstream sensor, a couple wires looked melted and 1 was completely broke off about 3 inches off the sensor itself. the back of the sensor is right up against a heat shield for the catalytic converter which may have caused it to melt off.... So i assumed it was that sensor that was causing the problem and went ahead and swapped it out with direct fit ntk sensor, it looked identical to the problem one. finished installing the new sensor and started my vehicle, the check engine light was still illuminated (original code p0038) . i turned the car off and unplugged the battery for roughly a minute to reset the pcm . started the car back up and the light had disappeared upon starting, i let it ran for a couple minutes and shut it off so i could start my rear brakes. work on my braeks for awhile and start the car back up so i can bleed the brakes and about 5 minutes into bleeding i hear the ding of the check engine light coming back on, this time a new code p0141. i dont know what happened, i thought i had done everything right except for maybe unplugging the battery during the removal/installation. Any ideas?