Subject: Some customers may comment on an illuminated Malfunction Lamp and/or an engine misfire/ticking noise. During inspection, technicians may find DTC P0300 set or in history.
Vehicle Involved: 2015–2019 Cadillac Escalade; 2016–2019 Cadillac CTS-V; 2014 Chevrolet Silverado 1500; 2014–2019 Chevrolet Corvette; 2015–2018 Chevrolet Silverado; 2015–2019 Chevrolet Suburban and Tahoe; 2016–2019 Chevrolet Camaro; 2019 Chevrolet Silverado LD; 2014 GMC Sierra 1500; 2015–2018 GMC Sierra; 2015–2019 GMC Yukon and Yukon XL; and 2019 GMC Sierra Limited, equipped with one of the following 5.3L engines (RPOs L83, L8B) or 6.2L engines (RPOs L86, LT1, LT4).
The issue may be caused by one of the following conditions:
- An Active Fuel Management (AFM) lifter that is mechanically collapsed and/or stuck
- Internal locking pin damage in the lifter, due to oil aeration
- A lifter that has collapsed and is stuck in the lifter bore
- A bent push rod
If the Service Information (SI) diagnosis does not isolate the cause of the concern, inspect for proper valve operation. Also, with the lifters removed from the engine, inspect the camshaft for damage. If found, replace the camshaft as per SI.
If the valve(s) is/are not moving, replace the Valve Lifter Oil Manifold and the affected bank of AFM lifters. Refer to Valve Lifter Oil Manifold Replacement and Valve Lifter Replacement in SI. If the lifter has spun the bore, the guides should also be replaced.
There are two approved processes for removing the lifter when it’s stuck in the bore:
- Use vice grips with a slide hammer. (Note: Do not pry on the sealing surface of the block, as own in the illustration.)
- Use vice grips with a small pry bar.
One of the above processes will typically work. If not, the engine will need to be replaced.
In addition, with the lifter removed, inspect the bore for any damage. The lifter bores will usually look good with no indication of damage.
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