about scan codes p0147 where is that sensor located also have codes p0300,p0440, on 1996 Chevrolet Blazer

also p1351 ignition control circuit high voltage also evaporative emission system code p0440. i would like too know how to fix those issues

Asked by for the 1996 Chevrolet Blazer
this obd2 trouble code table can help you understand the meaning of code.
for these codes, you can try.
1.Using a scan tool command the EGR valve to open while watching the actual EGR position (it will probably be labeled "desired EGR" or something similar). The actual EGR position should be very close to the "desired" EGR position. If it is, then the problem is likely intermittent. It may have been a lodged piece of carbon that has since dislodged, or it could be a bad EGR valve winding that intermittently opens or shorts as the valve temperature changes.
2.If the EGR "desired" position is not close to the "actual" position, then unplug the EGR sensor. Check for a good 5 Volt reference voltage to the connector. If it doesn't show a reference voltage, repair an open or short in the 5 Volt reference circuit.
3.If there is a 5 volt reference voltage, activate the EGR with the scanner, monitor the EGR ground circuit with a DVOM (Digital Volt/Ohm meter). It should indicate a good ground. If it doesn't then repair the ground circuit.
4.If there is a good ground, then check the control circuit. It should indicate voltage that varies according to the percentage that the EGR is open. As it's open more, the voltage should increase accordingly. If it does, then replace the EGR valve.
5.If the voltage doesn't increase incrementally, then repair open or short in EGR control circuit
1 more answer , 1 more comment
P-0147 Bank 1 Sensor 1 (upper) Oxygen sensor heater circuit
P-0300 Engine missfire (general code)
P-0440 Evap system fault
the Oxygen Sensor is simple fix , the Evap fault should be tested by a shop tracing leakes on the Evap can be a POS.... Try the O2 sensor first ....pull the battery cables to clear codes and see what comes back
thanks for the info very useful