GMC Yukon XL 2000–2006

From the manufacturer’s document

• Applies to：Applies to Buick, Cadillac, Chevrolet and GMC passenger cars and trucks, model years 2000 to 2022, gasoline engines only.
• Condition：Customers may comment that the MIL is illuminated.
• Condition：Initial diagnosis may show fuel trim and O2 sensor related codes including P0101, P0137, P0138, P0140, P0141, P0157, P0158, P0160 and P0161.
• Condition：The listed codes also include P0171, P0174, P0420, P0430, P1174 and P1175.
• Confirm：If normal SI diagnostics do not lead to a resolution and an intake vacuum leak or exhaust leak is suspected, use the GE-52250 Variable Pressure Leak Detector (preferred), the J-41416 ultrasonic leak tester, or possibly soapy water with low pressure air into the tailpipe to find the leak.
• Caution：All of these tests are much more effective if the throttle body is covered or sealed.
• Confirm：For an intake leak, introduce the smoke into the brake booster hose or the oil dipstick tube; soapy water can be sprayed near the gasket, seams and all vacuum nipples.
• Confirm：For an exhaust leak, put the hose with smoke or air into the tailpipe sealed with shop towels, then spray soapy water around seals, seams and bosses.
• Cause：These methods find small leaks around the O2 sensor embossments and slight cracks in an intake plenum or gasket.
• Parts：No parts are required for this repair.

From the manufacturer’s document

• Applies to：Applies to all brands and models with gasoline engines, model years 2000 - 2022.
• Applies to：The involved region is North America.
• Condition：In rare instances customers may complain of a fuel smell, longer starts, hesitation and, in extreme cases, engine stalls.
• Condition：Any combination of DTCs P0300, P0171, P0174 and P228C may be set.
• Cause：Using winter fuel in summer weather may cause drivability concerns.
• Confirm：The concern should not be a single event but multiple occurrences associated with hot days.
• Caution：No repair is required; the vehicles are not damaged and will recover.
• Caution：There is no other remedy until summer fuel and/or cooler weather is available.

From the manufacturer’s document

• Applies to：The list of compatible flexible-fuel vehicles includes 2002–2005 fullsize pickups and utilities with 5.3L, RPO L59.
• Applies to：The list of compatible flexible-fuel vehicles includes 2006 Sierra, Yukon and Yukon XL with 5.3L, RPO L59.
• Caution：All Model Year 2011 and older non-FFV gasoline vehicles are designed to run on fuel containing no more than 10% ethanol.
• Caution：Diesel engines are not E85 compatible.
• Condition：Using this fuel in a non-compatible vehicle may cause lean driveability concerns such as hesitation, sag and/or possible stalling.
• Condition：Fuel trim DTC P0171 and/or P0174 may set.
• Condition：Misfire DTC P0300 may set.
• Condition：A Traction Control, Stability System or ABS lamp may illuminate, or a message may display in the DIC (if equipped).
• Condition：Harsh and/or firm transmission shifts may occur because the transmission defaults to maximum line pressure.
• Confirm：Alcohol content is checked using Special Tool J-44175-A Fuel Composition Tester or CH-44175-A Fuel Composition Tester.
• Repair：If the ethanol content exceeds the Owner Manual maximum of 10% or 15%, drain the fuel and refill the vehicle with gasoline, preferably a Top Tier brand.
• Confirm：General Motors started putting yellow gas caps on E85 Flex Fuel Vehicles (FFVs) as of Model Year 2006.