GM Service Manual Online
For 1990-2009 cars only

Inspection Procedure

Whenever the EVAP DTC diagnostics lead to a no trouble found or a purge solenoid replacement, proceed with the following charcoal canister diagnostics.

Notice: Use the EVAP Pressure/Purge Diagnostic Station J 41413 in order to provide a clean, dry, low pressure gas source. Do not substitute any other pressurized gas source. Damage may result to the EVAP system.


    Object Number: 20803  Size: SH
  1. Turn OFF the ignition.
  2. Remove the EVAP canister purge solenoid from the vehicle. Refer to Evaporative Emission Canister Purge Solenoid Valve Replacement .
  3. Lightly tap the EVAP canister purge solenoid on a clean work area.
  4. Look for carbon particles existing from either of the vacuum ports.
  5. If no carbon release is evident, reinstall the components. Continue with the published service manual DTC procedures.
  6. If carbon is being released from either component, continue with this service procedure.
  7. Remove the charcoal canister from the vehicle. Refer to Evaporative Emission Canister Replacement .
  8. Turn off the main cylinder valve (1) on the EVAP purge/pressure diagnostic station. Refer to J 41413 .
  9. Disconnect the black hose (4) that connects the nitrogen cylinder to the cart, refer to J 41413 at the pressure regulator (5).
  10. Using a section of the vacuum hose, connect one end onto the open fitting of the, refer to J 41413 pressure regulator (5).
  11. Connect the other end of the vacuum line side of the EVAP purge line at the vehicle.
  12. Turn on the main nitrogen cylinder valve (1).
  13. Continue to blow any debris from the purge line for 15 seconds.
  14. Return the J 41413 to its original condition by re-installing the black hose (4) disconnected in step 9.
  15. Replace the EVAP purge solenoid refer to Evaporative Emission Canister Purge Solenoid Valve Replacement and the charcoal canister refer to Evaporative Emission Canister Replacement with the new components.