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P1639 Diagnostic Trouble Code Discussion for July 2013

5-Volt Reference 'B' Circuit Malfunction

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Trouble Ticket Help Requests for DTC P1639
Help Request Posted
2002 Chevrolet Impala LS 3.8L MIL Lamp on VIN: 2G1WH55K12
P1639: 5-Volt Reference 'B' Circuit Malfunction. ... checked for the 5v on each of the sensors,fuel tank pressure sensor,A/C high side pressure sensor,EGR valve ,TPS,and MAP sensor all good.If I disconnect one at a time and start car both the p1635 p1639 codes set immediatly...
July 01, 2013