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HOMESERVICE MANUALSGMC1999FORWARD CONTROL 5.7 R, AUTOMATICREPAIR AND DIAGNOSISEXTERNAL PAGESDIFFERENT CARSECTION 86 (ENGINE CONTROLS - SELF-DIAGNOSTICS - 3.0L)DIAGNOSTIC TESTSDTC P0442: EVAP SYSTEM - SMALL LEAK DETECTEDDTC PARAMETERS
1999 GMC Forward Control 5.7 R, Automatic

DTC Parameters

1999 GMC Forward Control 5.7 R, AutomaticSECTION DTC Parameters
WARNING: This page is about a different car, the 2002 Saturn Vue. However, it is still accessible from the selected car via links, so may be relevant.
  • EVAP purge solenoid is commanded off.
  • EVAP vent solenoid is commanded on.
  • Engine is at idle.
  • Vehicle speed is zero MPH.
  • Volumetric efficiency is less than 35 percent.
  • Main relay voltage is more than 10 volts.
  • ECT at start-up is 40-131°F (4-55°C).
  • IAT is 40-140°F (4-60°C).
  • Fuel tank pressure is -7.23-3.61 in. H2O to enable test.
  • Long term fuel cells learned (if not learned, engine must run longer than 16 minutes 45 seconds).
  • Fuel level is 2.4-13.4 gallons.
  • No ECT, EVAP purge solenoid, EVAP vent solenoid, fuel tank pressure, idle speed HO2S, throttle actuator, TP sensor or vehicle speed DTCs have been set.

DTC sets if the vacuum decay is greater than a calibrated amount over a 3 second period during phase E of the EVAP diagnostic system test indicating a small EVAP leak. Condition exists for the entire phase E of 3 seconds.

The entire EVAP diagnostic test will take about 16 seconds to complete when no errors have been detected. If the P0442 diagnostic fails, the rest of the EVAP diagnostic test is aborted and not run again in the ignition cycle.

If an EVAP diagnostic test is aborted due to changing enable criteria, the ECM will run the EVAP diagnostic test up to 10 times per ignition cycle.

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When to See a Mechanic

Stop DIY work and contact a certified mechanic immediately if any of the following apply:

  • • You smell fuel, burning insulation, or see smoke.
  • • Brakes feel soft, pull hard to one side, or make grinding noises.
  • • The engine overheats, stalls repeatedly, or misfires under load.
  • • You are missing required tools, torque specs, or safe lifting equipment.
  • • You are not confident in the next step or safety outcome.