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2001 Chevrolet Suburban 1500 5.3L 2003 GMC Yukon 5.3L, FLEX, Vin Z 2003 Cadillac Escalade 6.0L, Vin N, 2003 GMC Yukon XL 1500 5.3L, FLEX, Vin USA/Canada Z 1. Check for leaking intake manifold seals around the intake ports. The intake gasket seals may be leaking around the intake ports, causing a lean condition. Many times they will leak around the bottom side of the port, making it a challenge to detect the vacuum leak. May also note lower than normal Mass Airflow (MAF) readings if the seals are leaking around the ports. 2. If leaking intake gasket seals are found, replace the gaskets with the updated part number.

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ISSUE Some 2001-2005 Taurus/Sable, 2001-2006 Escape and 2005-2006 Mariner vehicles built prior to
1-17-2006 equipped with the 3.0L 4V Duratec engine may exhibit a ticking noise from the left bank cylinder head, with the engine at normal operating temperature only.
ACTION To diagnose, with the engine running and warm (normal operation temperature), using a mechanic’s stethoscope determine if the ticking noise is coming from the left hand intake camshaft at cylinder number 6, (Figure 1). If the ticking noise can be verified, refer to the following Service Procedure.

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Test Description The numbers below refer to the step numbers on the diagnostic table. 2. Allow the engine to cool before performing this test. If the sensor is at the operating temperature, the HO2S voltage will stay high or low. If the HO2S voltage stays between 300-700 mV this indicates the HO2S heater is inoperative. 3. If more than one HO2S DTC is set, this is a good indication that the HO2S fuse is open. Test all the related circuits going to all the heated oxygen sensors for a short to ground. If you cannot locate a shorted circuit, it may be necessary to disconnect each HO2S one at a time to locate a shorted sensor. 4. This step determines if an ignition positive voltage supply is available at the sensor.

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2001-2002 Chevrolet Camaro 2001-2003 Chevrolet Corvette 2001-2002 Pontiac Firebird 2002-2003 Cadillac Escalade, Escalade EXT
2000-2003 Chevrolet Suburban, Tahoe 2001-2003 Chevrolet Silverado 2002-2003 Chevrolet Avalanche 2000-2003 GMC Yukon, Yukon XL 2001-2003 GMC Sierra with 4.8L, 5.3L, 5.7L or 6.0L V8 Engine (VINs V, T, Z, G, S, N, U – RPOs LR4, LM7, L59, LS1, LS6, LQ9, LQ4)
Condition Some customers may comment on an engine tick noise. The distinguishing characteristic of this condition is that it likely will have been present since new, and is typically noticed within the first 161-322 km (100-200 mi). The noise may often be diagnosed as a collapsed lifter. Additionally, the noise may be present at cold start and appear to diminish and then return as the engine warms to operating temperature. This noise is different from other noises that may begin to occur at 3219-4828 km (2000-3000 mi).

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Steering Vibration/Shudder/Moan During Parking Maneuvers on Dry Pavement (Install Power Steering Pressure (Inlet) and/or Return (Outlet) Hose Assembly) 1995-99 Buick Riviera 1997-2001 Buick Park Avenue, Ultra 2000-2001 Buick LeSabre 2000-2001 Pontiac Bonneville steering vibration, shudder or moan noise when steering during parking maneuvers on dry pavement. Correction Install a new power steering pressure (inlet) hose assembly on the following vehicles: • 1995-98 Buick Riviera • 1997-98 Buick Park Avenue and Ultra Install a new power steering pressure (inlet) and return (outlet) hose assembly on the following vehicles: • 1999 Buick Riviera • 1999-2001 Buick Park Avenue and Ultra • 2000-2001 Buick LeSabre • 2000-2001 Pontiac Bonneville 1. Verify that the power steering pump reservoir is full. • If fluid level is low, fill and check for leaks. • If power steering system has air in the system, perform the “Bleeding Air from Power Steering System” procedure as described in the Power Steering System sub-section of the Service Manual. Important: When performing the “Bleeding Air from Power Steering System” procedure, it is important that the front of the vehicle is supported by the lower control arms. If the vehicle is not supported by the lower control arms, the procedure may cause the strut bushing to dislocate and cause new concern. Verify that the accessory drive belt is in good condition and that the pulleys are not bent or damaged. Verify proper belt tension and operation of the belt tensioner. Check for power steering hose ground out conditions. Check for good engine idle and correct engine RPM. Check to see that the rear transaxle mount does not have a plastic assembly aid installed which is used 2. 3. 4. 5. 6.