In this video I will be showing you how to test for an EVAP system leak, using a smoke machine. Also we will be covering how to identify the normally open solenoid that is part of every EVAP system. This solenoid must be closed (all cars) either manually or with a scan tool before attempting to locate an EVAP leak.

Engine Performance Diagnostics chapter 3 "Transistor Drivers and Output Solenoids"


  • check engine light (P0455)
  • fuel smell

fix 50

  • replace faulty vacuum cut valve-bypass valve (solenoid)

test shown

  • how to close a vent solenoid to perform a smoke test of the EVAP system
  • how to locate the vent solenoid
  • how to locate and test the vacuum cut valve bypass valve solenoid
  • how to test the wiring and transistor that controls the vacuum cut valve bypass valve

Tools used

  • Verus Edge
  • Smart Smoke evaporative emission tester
  • Power Probe IV
  • Power Probe lead set

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(Chapter 3) Transistors, Solenoids, Computer Controlled Output Testing

Related videos:

EVAP Leak Testing (P0455, P0440, P0442):


EVAP Leak Test P0455:


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


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


GM EVAP Vent Solenoid Testing:


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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.

Want even more diagnostic training? Whether you are a DIY trying to fix your own car, someone looking to become an auto technician, or a current auto technician that wants to get more into diagnostics, subscribe to ScannerDanner Premium. There is a 14 day free trial.

On ScannerDanner Premium I will bring you right into my classroom at Rosedale Technical College. You will find page for page lectures taken right from my book as well as exclusive classroom type case studies. What is so special about these classroom case studies? I pull live problem vehicles directly into my classroom and we troubleshoot them in real time, using and applying the theory and testing procedures we learn during the classroom lectures. There is no better on-line training of how to troubleshoot automotive electrical and electronics systems anywhere!