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Home >> Saturn >> 2002 >> L300 >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - Self-Diagnostics >> Diagnostic Tests >> DTC P0446: EVAP Vent System Performance >> Diagnostic Procedures
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Diagnostic Procedures

NOTE: If DTC P0440, P0442, P0446 or P0455 is set, EVAP special functions on scan tool will not be allowed. Clear DTCs before performing these tests.
  1. Turn ignition on, engine off. Remove fuel cap. Using scan tool, monitor FTP SENSOR. If voltage is 2.35-2.85 volts, go to next step. If voltage is less than 0.2 volt, see DTC P0452: EVAP FUEL TANK PRESSURE SENSOR CIRCUIT - LOW VOLTAGE  . If voltage is 0.2-2.35 volts or 2.85-4.9 volts, replace FTP sensor. If voltage is more than 4.9 volts, see DTC P0453: EVAP FUEL TANK PRESSURE SENSOR CIRCUIT - HIGH VOLTAGE  .
  2. Install fuel cap. Clear ECM DTCs. Start engine and let idle. Using scan tool, perform EVAP PURGE/SEAL special function by commanding a 10 percent duty cycle to the EVAP purge solenoid. Wait for fuel tank pressure to reach 1.8 volts or less, then using scan tool, command EVAP purge solenoid OFF by pressing EXIT. If fuel tank pressure returns to 2.35-2.85 volts within 5 seconds, problem is intermittent. See DIAGNOSTIC AIDS  . If fuel tank pressure does not return to 2.35-2.85 volts within 5 seconds, go to next step.
  3. Turn ignition on, engine off. Remove right rear inner fender well. Raise vehicle to chest height. Using scan tool, command EVAP VENT SOLENOID on and off while listening for the solenoid clicking at the right rear inner fender area. If the solenoid clicks, EVAP vent system is blocked. Check EVAP vent box hose for at pinched of kinked condition, and blocked EVAP canister or kinked/pinched EVAP lines/hoses between EVAP vent solenoid and EVAP canister. If solenoid does not click, replace EVAP vent solenoid.
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