I ran a Diagnostic on my 1998 chevy venture mini

my 1998 chevy venture is marking service engine soon light, ABS light , and oil light regardless if the oil is at its normal filled level

the 2 codes are

P0134 02 Sensor Circuit no activity Detected (bank 1 sensor 1)
first check your fuses check the wiring to the sensor(the sensor is on the exhaust in front of the engine-open the hood and look down) if the fuses and the wiring look good replace the O2 sensor there are 2 types of sensors original equipment(oe) style and universal the oe style has a connector you just plug in, the universal you have to hard wire in

the 2nd code is Mass Air Flow (MAF) Circuit Low Input
check the wireing, make shure theres a good connections
you said that you already replaced this sensor so im going to recomend that you go after the other code first

deal with the oxygen sensor then reset the computer and see what codes come back