P06DD: How to Diagnose & Fix — Engine Oil Pressure Control Circuit Stuck Off

GM's Active Fuel Management (AFM) system deactivates cylinders to improve fuel economy, but can cause premature lifter wear and failure. Symptoms include rough idle, misfires, and valve train noise. GM released updated lifters.

The GMC Yukon 5.3L (L83, LC9, LMG) and 6.2L (L94, L86) V8 engines use Active Fuel Management (AFM) cylinder deactivation. The special collapsible AFM lifters on cylinders 1, 4, 6, and 7 fail prematurely, causing misfires, engine ticking, rough idle, and potential catastrophic damage. This is the single most reported mechanical failure on GMT900 (2007-2014) and K2XX (2015-2020) Yukon models. GM issued diagnostic bulletins PIP4568 (2007-2014 AFM V8s) and PIP5259 (2014-2015 Yukon) covering collapsed or stuck AFM lifters. Yukon models used as daily drivers with lots of highway cruising (where AFM activates most) are most susceptible. On 2007-2014 engines the VLOM (Valve Lifter Oil Manifold), which controls oil flow to the AFM lifters, is replaced along with the lifters per PIP4568.

2016-2017 Lincoln MKX models with the 2.7L EcoBoost V6 (engines built roughly April 2016 to January 2017) can suffer excessive oil consumption caused by defective cylinder head valve guides that let oil seep into the combustion chamber and burn off. Owners report burning roughly a quart every 3,000 miles, often accompanied by rough idle, misfires, and blue/white exhaust smoke. Ford addressed this in Technical Service Bulletin 19-2243, whose official remedy is replacement of both left and right cylinder heads. Fouled spark plugs from oil contamination commonly trigger cylinder-specific misfire codes.

The 3.8L V6 (used in 2007-2011 JK Wranglers) is widely reported to consume oil, with affected examples burning roughly a quart every 1,000-2,000 miles while others see little loss. Owners and forum techs attribute it to the low-tension piston rings combined with the U.S. 5W-20 oil specification (Jeep specs heavier 5W-30 in export markets), which lets thin oil slip past the rings and burn. In severe cases low oil from unnoticed consumption contributes to ticking, spun main bearings, or ring failure, so monitoring level between changes is important.

The Tahoe 5.3L and 6.2L V8 engines with Active Fuel Management (AFM) use collapsible hydraulic lifters that commonly fail between 80,000-120,000 miles. Failed AFM lifters cause misfires on deactivation cylinders (1, 4, 6, 7), ticking noises, and potential camshaft and cylinder wall damage. This is the same issue affecting the Silverado and Escalade. GM issued Service Bulletin 15-06-01-002O for 2015-2020 Tahoes with the 5.3L (L83) or 6.2L (L86), acknowledging collapsed or stuck AFM lifters. GM's bulletin calls for replacing the affected bank of AFM lifters (with new lifter guides), and the Valve Lifter Oil Manifold (VLOM) only when diagnosis finds a fault in it; the camshaft is replaced if lobes or rollers are worn.