A common problem with these EVAP vent valves is a broken wire inside of the insulation! The wiring will look completely fine until you pull on the harness. In this video I will show you how to troubleshoot and repair this condition.

Engine Performance Diagnostics chapter 3

Topics discussed


  • check engine light (P0449 trouble code)


  • repair broken wire to the EVAP vent solenoid

test shown

  • how to repair a broken wire right at the connector
  • how to repair a wiring connector
  • how to test an EVAP vent solenoid (valve)
  • how to determine power and ground side switching
  • how to test the computer driver (transistor)
  • how to use scan data to ID an open circuit
  • how to use the "driver test" mode in the Power Probe IV
  • how to use a scan tool in a bi-directional test mode

Tools used

end faq

Related videos:

1997 Dodge Neon no start, crank sensor problems (repair of broken wires at the crank sensor connector shown):

(EVAP) Vent Solenoid Control Circuit P0449 repair - GM:

How to test an EVAP Vent solenoid (applies to all cars) - GM:

2008 Chevy Avalanche EVAP Vent Solenoid Test (P0449, P0455):

end faq



EVAP System Testing

For more information on this topic, I have written a “field manual” called Engine Performance Diagnostics which is available as an eBook or paper book.

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