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PO 446 Code

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Mar 14, 2010, 4:28 PM

Post #1 of 2 (7187 views)
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Hi everyone I got a PO 446 code what is it and what do I need to do it's a 2000 buick park avenue 3.8 series II with 104200 miles on it thanks

Hammer Time
Ultimate Carjunky / Moderator

Mar 14, 2010, 9:06 PM

Post #2 of 2 (7174 views)
Re: PO 446 Code [In reply to] Sign In

The EVAP system includes the following components:
  • The fuel tank.
  • The EVAP vent valve.
  • The fuel pipes and hoses.
  • The fuel fill cap.
  • The EVAP vapor pipes.
  • The EVAP purge pipes.
  • The EVAP canister.
  • The EVAP canister purge valve.

A RESTRICTED or BLOCKED EVAP VENT PATH is detected by monitoring fuel tank pressure during normal operation (EVAP vent valve open, EVAP canister purge valve normal). With the EVAP vent valve open, vacuum level in the system should be very low unless the vent path is blocked.

The following conditions will set DTC P0446.
  • Faulty EVAP vent valve (stuck closed).
  • Plugged kinked or pinched vent hose.
  • Shorted EVAP vent valve driver circuit.
  • Plugged EVAP canister.

All conditions for P0440 and P0442 have been met and passed.

  • fuel tank pressure is less than -10 in. H2O.
  • The condition is present for up to 30 seconds.

  • The PCM will illuminate the Malfunction Indicator lamp (Mil) during the second consecutive trip in which the diagnostic test has been run and failed.
  • The PCM will store conditions which were present when the DTC set as Freeze Frame/Failure Records data.

  • The PCM will turn the MIL OFF during the third consecutive trip in witch the diagnostic has been run and passed.
  • The history DTC will clear when the PCM turns OFF the Mil.
  • The DTC can be cleared by using the scan tool.

Check for the following conditions:
  • Kinked, pinched or plugged vent hose.
  • Reviewing the Fail Records vehicle mileage since the diagnostic test last failed may help determine how often the condition that caused the DTC to be set occurs. This may assist in diagnosing the condition.

Inspect for charcoal release from the EVAP canister.

Number(s) below refer to the step number(s) on the Diagnostic Table:
  1. The Powertrain On Board Diagnosis (OBD) System Check promps you to the basic checks and store the Freeze Frame and Failure Records Data on the scan tool if applicable.
  1. Tests the EVAP canister purge valve for a small vacuum source during non purge.
  1. Tests the EVAP vent valve for a restriction or blockage.


We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.

PO 446 Code

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