hello i have a 1998 v70 with 177,00 mi,, i just clean the air mass sensor and replaced the front 02 sensor and clear the code,s that i had check/lite went off drove the 3mi ,, and now lite is back on now the code is p0131 low volt,s can any 1 explain this 1 to me why with a new sensor i would be geting this code is the front sensor the 1 in front of the engine it say bank 1 with the code any help out ther,,,

 

OEM sensor?

 

check the rear sensor wires for rust etc. I had the same problem low reading on front and actually the rear 0 2 sensor was bad. Just like tech said always go with oem 02 sensors. The after market will just drive you insane to trouble shoot.