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Home >> Saturn >> 2002 >> SC2 Automatic, MP6 >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - Self-Diagnostics >> Diagnostic Tests >> DTC P0440: EVAP System >> Diagnostic Procedure
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Diagnostic Procedure

NOTE: If DTCs P0444, P0445, P0447 or P0448 are also set, diagnose these DTCs first. See DTC P0444: EVAP PURGE VALVE CONTROL CIRCUIT OPEN  , DTC P0445: EVAP PURGE VALVE CONTROL CIRCUIT SHORTED  , DTC P0447: EVAP VENT VALVE CONTROL CIRCUIT OPEN  or DTC P0448: EVAP VENT VALVE CONTROL CIRCUIT SHORTED  .
  1. Turn ignition on, engine off. Remove fuel cap. Using scan tool, monitor FUEL TANK PRESS. SENSOR. If voltage is 1.3-1.7 volts, go to next step. If voltage is less than 0.1 volt, see DTC P0452: EVAP FUEL TANK PRESSURE SENSOR CIRCUIT - LOW VOLTAGE  . If voltage is 0.1-1.3 volts or 1.7-4.9 volts, replace fuel tank pressure sensor. If voltage is greater than 4.9 volts, see DTC P0453: EVAP FUEL TANK PRESSURE SENSOR CIRCUIT - HIGH VOLTAGE  .
  2. Install fuel cap. Start engine. Using scan tool, perform EVAP VENT TEST. Using scan tool, monitor FUEL TANK PRESS. SENSOR. If voltage is 3.5 volts or more after 30 seconds, fuel cap is not installed properly or is leaking. If voltage does not reach 3.5 volts in 30 seconds, go to next step.
  3. Turn ignition on, engine off. Using scan tool, perform EVAP SYSTEM SEAL. Connect EVAP Pressure/Purge Diagnostic Cart (J 41750-SAT) to EVAP service port. Pressurize system to 30 in. H2O, then switch to hold position. If system reaches 8 in. H2O pressure, vacuum source to EVAP system is faulty. Check vacuum hose to EVAP purge solenoid for leaks, plugged EVAP purge throttle solenoid vacuum port and EVAP purge solenoid for a stuck closed valve. If system does not reach 8 in. H2O, use EVAP pressure/purge diagnostic cart and ultrasonic leak detector to locate large leak.
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