A flashing check engine light combined with P0171 on your 2018 Ram 2500 indicates an urgent condition requiring immediate attention. The flashing light signals active misfires caused by a lean fuel mixture, threatening catalytic converter damage. For the 6.4L Hemi engine, this represents a serious situation.
Flashing Light Urgency
The check engine light flashes when misfire severity threatens immediate catalyst damage. Unburned fuel from lean misfires enters the exhaust and burns in the catalytic converter, creating temperatures that destroy the internal substrate. Stop driving immediately.
P0171 Lean Bank 1
P0171 indicates bank 1 of the 6.4L Hemi V8 is receiving insufficient fuel relative to air. The ECM attempts compensation by adding fuel, but when limits are exceeded, the lean code triggers. Combined with severe enough misfires to cause flashing, immediate diagnosis is critical.
Common Lean Causes in the 6.4L
Vacuum leaks at the large intake manifold or brake booster line introduce unmetered air. Mass airflow sensor contamination causes incorrect air measurement. Fuel delivery problems from pump weakness or injector restrictions reduce fuel supply. The MDS system can create unusual conditions.
Heavy-Duty Considerations
The 6.4L Hemi in the 2500 operates under demanding conditions with heavy loads and towing. Lean conditions under these loads create extreme stress. Don't tow or load the vehicle until repairs are complete.