GMC Yukon 2000–2006

▸ENGINE AND ENGINE COOLING2

1. Manufacturer communication2000–2006 GMC YUKON DENALI ・ 2023-01-06(2 earlier editions of this document folded here)

   EVAP Leak Diagnostic Service Bulletin (DTCs P0442/P0455)

   1. 1Fault

      • Leak
      • Warning light
      • P0442
      • P0455 (general documents only)
      • The MIL is illuminated, and DTC P0442 (EVAP small leak detected) and/or P0455 (EVAP large leak detected) may be set in the ECM.
      ↓→

   2. 2Finding the cause

      Possible causes

      • P0455 sets because of a large leak or a purge blockage: an unseated tube connection, a damaged tube, a canister vent valve stuck open, or a purge valve stuck closed.
      • P0442 sets because of a small leak, which can come from a purge valve stuck open or a canister vent valve stuck open.

      Steps to confirm (in the document’s order)

      1. Inspect every purge connection for proper installation, and look along the lines for damage or wear; if damage is seen, confirm it with the smoke test.
      2. Some leaks show only under pressure and some only under vacuum, so check both ways; cycling the purge and vent solenoids with GDS2 while inspecting may show a sticking valve.
      3. Critical connections to check include: purge tube to purge valve (at the intake manifold), purge tube to chassis EVAP line (rear of the engine, near the transmission), chassis EVAP line to canister, and fuel tank load line to canister.
      4. Also check the vent valve line at the vent valve, the fuel tank load line jumper connection near the fuel tank, and that the fuel tank cap is closed properly.
      5. If all connections are good, check the vent valve for a stuck-open position; if the vent valve works correctly, go on to the purge valve.

      1 more points
      ↓→

   3. 3Correction

      Parts

      • No parts are required for this repair.

      Caution

      • For diagnostic instructions, DTC information and required tools, always follow the service information document for the vehicle and DTC being worked on.
   Read the sentences of the record

   From the manufacturer’s document

   • Applies to：This bulletin only applies to vehicles with gasoline engines.
   • Condition：The MIL is illuminated, and DTC P0442 (EVAP small leak detected) and/or P0455 (EVAP large leak detected) may be set in the ECM.
   • Cause：P0455 sets because of a large leak or a purge blockage: an unseated tube connection, a damaged tube, a canister vent valve stuck open, or a purge valve stuck closed.
   • Cause：P0442 sets because of a small leak, which can come from a purge valve stuck open or a canister vent valve stuck open.
   • Confirm：Inspect every purge connection for proper installation, and look along the lines for damage or wear; if damage is seen, confirm it with the smoke test.
   • Confirm：Some leaks show only under pressure and some only under vacuum, so check both ways; cycling the purge and vent solenoids with GDS2 while inspecting may show a sticking valve.
   • Confirm：Critical connections to check include: purge tube to purge valve (at the intake manifold), purge tube to chassis EVAP line (rear of the engine, near the transmission), chassis EVAP line to canister, and fuel tank load line to canister.
   • Confirm：Also check the vent valve line at the vent valve, the fuel tank load line jumper connection near the fuel tank, and that the fuel tank cap is closed properly.
   • Confirm：If all connections are good, check the vent valve for a stuck-open position; if the vent valve works correctly, go on to the purge valve.
   • Confirm：Work in this order: EVAP lines properly installed and fully seated; damage on the EVAP lines; vent valve malfunction; purge valve malfunction.
   • Parts：No parts are required for this repair.
   • Caution：For diagnostic instructions, DTC information and required tools, always follow the service information document for the vehicle and DTC being worked on.

   Open the manufacturer’s document (PDF) ↗ The points above were read from this document.

   Remedy

   This service bulletin provides diagnostic tips/steps on testing for possible EVAP leaks in the system to correct a customer concern of an MIL Illuminated with DTCs P0442 and/or P0455 Set.

2. Manufacturer communication2000–2006 GMC YUKON DENALI ・ 2017-08-15(1 earlier editions of this document folded here)

   Engine Check Lamp P0442 Evaporative Emissions System Notification

   1. 1Fault

      • Gauge or instrument fault
      • Leak
      • Smoke or fire
      • Warning light
      • Check engine / Service Engine Soon
      • P0442
      • The service engine soon lamp (MIL) is on for DTC P0442, but a leak cannot be verified with the system test in the service information.
      ↓→

   2. 2Finding the cause

      Steps to confirm (in the document’s order)

      1. With the scan tool, command the EVAP system CLOSED, start the engine and watch the tank pressure sensor value for about two minutes.
      2. If the tank pressure value changes (shows vacuum), remove the purge solenoid and pressurize its fuel tank side with the GE 41413-A / J 41413-A tester.
      3. If the tank pressure value does not change, install the CH-48096 adaptor between the purge line from the canister and the purge solenoid; use no other adaptor or pressurization method.
      4. With the EVAP system CLOSED, pressurize through the adaptor and let the system stabilize, watching the gauge for at least 5 minutes, then add smoke.
      5. Look for smoke or UV trace fluid at the purge solenoid, the engine side, the fuel cap or capless fill door, and the canister vent solenoid filter or fresh-air line.

      1 more points
      ↓→

   3. 3Correction

      • Purge Solenoid: replaced

      Repair

      • If smoke passes through the purge solenoid, replace the purge solenoid.

      Caution

      • After verifying P0442, do not disturb any fuel system component before testing.
      • Test pressure must not exceed 13 in H2O (0.5 PSI (= 3.45 kPa)); more can make components perform inaccurately and lead to misdiagnosis.
      • A large temperature difference between vehicle, shop and tester seriously affects accuracy; let the vehicle adjust to shop temperature first.
   Read the sentences of the record

   From the manufacturer’s document

   • Applies to：Applies to 2016 and prior passenger cars and trucks.
   • Condition：The service engine soon lamp (MIL) is on for DTC P0442, but a leak cannot be verified with the system test in the service information.
   • Caution：After verifying P0442, do not disturb any fuel system component before testing.
   • Confirm：With the scan tool, command the EVAP system CLOSED, start the engine and watch the tank pressure sensor value for about two minutes.
   • Confirm：If the tank pressure value changes (shows vacuum), remove the purge solenoid and pressurize its fuel tank side with the GE 41413-A / J 41413-A tester.
   • Repair：If smoke passes through the purge solenoid, replace the purge solenoid.
   • Confirm：If the tank pressure value does not change, install the CH-48096 adaptor between the purge line from the canister and the purge solenoid; use no other adaptor or pressurization method.
   • Confirm：With the EVAP system CLOSED, pressurize through the adaptor and let the system stabilize, watching the gauge for at least 5 minutes, then add smoke.
   • Confirm：Look for smoke or UV trace fluid at the purge solenoid, the engine side, the fuel cap or capless fill door, and the canister vent solenoid filter or fresh-air line.
   • Confirm：If smoke testing finds nothing, the leak may exist only under vacuum: use the scan tool Purge/Seal function to pull a vacuum and watch the FTP sensor parameter for vacuum decay.
   • Caution：Test pressure must not exceed 13 in H2O (0.5 PSI (= 3.45 kPa)); more can make components perform inaccurately and lead to misdiagnosis.
   • Caution：A large temperature difference between vehicle, shop and tester seriously affects accuracy; let the vehicle adjust to shop temperature first.

   Open the manufacturer’s document (PDF) ↗ The points above were read from this document.

   Remedy

   This Preliminary Information communication provides information to the technician about vehicles that have a Service Engine Soon Malfunction Indicator Lamp. Technician may find Diagnostic Trouble Code P0442. Technician will need to review Techlink article from May 2013 titled "Using the Evaporative Emissions System Tester" Technician will need to follow these steps to help diagnose the issue. First after the P0442 has been verified do not disturb any of the fuel system components. The technician now can use the scan tool to close the Evaporative Emissions System. If possible change the tank pressure sensor units from inch_H2O to milimeter_Hg for better resolution. Now the vehicle can be stared to monitor the tank pressure sensor output value for approximately two minutes. If the tank pressure sensor value does change, pressurize the fuel tank side of the purge solenoid with the GE 41413-A / J 41413-A and the necessary adaptors. Now add smoke and allow pressure to stabilize for 2 minutes. If smoke is allowed to pass through the purge solenoid, replace the purge solenoid. If the tank pressure sensor value does not change, then install CH-48096 adaptor between the purge line from the canister and the purge solenoid. With the Evaporative Emissions System closed, pressurize the system through the CH-48096 adaptor and allow the system to completely stabilize, by observing the Press / Vac Gauge for a minimum of 5 minutes. Now add smoke to the system with GE 41413-A / J 41413-A after system stabilization. Now inspect the purge solenoid, engine side, fuel cap, canister vent solenoid filter and any line quick connects. When the leak is unable to be located, test under a vacuum condition. his type of leak may be detected by using the scan tool Purge/Seal function to create a vacuum in the Evaporative Emissions System and then observe the FTP sensor parameter for vacuum decay.