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P1491 Diagnostic Trouble Code Discussion for September 2008

EVAP Vacuum Cut Valve/Bypass Circuit Malfunction

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Trouble Ticket Help Requests for DTC P1491
Help Request Posted
2002 Nissan Pathfinder SE 3.5L MIL Lamp on VIN: JN8DR09Y12
P1491: EVAP Vacuum Cut Valve/Bypass Circuit Malfunction. Hoping some Nissan techs out there can tell me what is the most common causes of the PO1491. A dealership told this customer that it needed the vac cut bypass valve replaced so being a good pal I believed them and replaced it. Couple days later they called and...
September 11, 2008
2001 Nissan Pathfinder LE 3.5L MIL Lamp on VIN: JN8DRO7Y41
P1491: EVAP Vacuum Cut Valve/Bypass Circuit Malfunction. ... sensors and the maf sensor codes po300, po171, p1145 all went away, But were replaced with p1491 (evap) po420 (cat efficiency) po430 (cat efficiency)..These "new codes" make me suspect that the system is doing a more complete self test now that the...
September 23, 2008
2000 Dodge Durango R/T 5.9L MIL Lamp on VIN: 1B4HS28Z7Y
P1491: Cooling Fan Control Relay Circuit Malfunction. Hello all: I have a customer with a 2000 Durango which has the MIL light on constantly. The light comes back on immediately after the code is cleared and this will result in an immediate Aircare test failure. I have pulled the entire harness between the comput...
September 25, 2008