GMC Yukon XL 2000–2006

▸ELECTRICAL SYSTEM1

1. Manufacturer communication2000–2006 GMC YUKON XL ・ 2021-07-06

   EVAP System Leak Diagnosis for MIL with 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) is set in the Engine Control Module (ECM).
      ↓→

   2. 2Finding the cause

      Possible causes

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

      Steps to confirm (in the document’s order)

      1. Inspect all purge connections for proper installation and look for damage or wear along the lines; if damage is seen, confirm with the smoke test.
      2. Some leaks show only under pressure and some only under vacuum, so check both ways.
      3. Cycling the purge and vent solenoids with GDS2 while inspecting may indicate a sticking valve.
      4. Critical connections on the engine side: purge tube to purge valve at the intake manifold, purge tube to chassis EVAP line at the rear of the engine near the transmission, and chassis EVAP line to canister.
      5. Critical connections on the tank side: fuel tank load line to canister, vent valve line to vent valve, fuel tank load line jumper connection near the fuel tank, and the fuel tank cap being closed properly.

      2 more points
      ↓→

   3. 3Correction

      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.

   Read the sentences of the record

   From the manufacturer’s document

   • Applies to：Applies to GM passenger cars and trucks, including medium duty, model years 2000 to 2021.
   • Applies to：The bulletin applies only to vehicles with gasoline engines.
   • Condition：The MIL is illuminated and DTC P0442 (EVAP small leak detected) and/or P0455 (EVAP large leak detected) is set in the Engine Control Module (ECM).
   • Cause：DTC P0455 sets for a large leak or a purge blockage; a large leak can come from an unseated tube connection, a damaged tube, a stuck open canister vent valve or a stuck closed purge valve.
   • Cause：DTC P0442 sets for a small leak, which can come from a stuck open purge valve or a stuck open canister vent valve.
   • Confirm：Inspect all purge connections for proper installation and look for damage or wear along the lines; if damage is seen, confirm with the smoke test.
   • Confirm：Some leaks show only under pressure and some only under vacuum, so check both ways.
   • Confirm：Cycling the purge and vent solenoids with GDS2 while inspecting may indicate a sticking valve.
   • Confirm：Critical connections on the engine side: purge tube to purge valve at the intake manifold, purge tube to chassis EVAP line at the rear of the engine near the transmission, and chassis EVAP line to canister.
   • Confirm：Critical connections on the tank side: fuel tank load line to canister, vent valve line to vent valve, fuel tank load line jumper connection near the fuel tank, and the fuel tank cap being closed properly.
   • Confirm：If all connections are good, check the vent valve for a stuck open position.
   • Confirm：If the vent valve is verified to be functioning correctly, go on to investigate the purge valve.

   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.