Buick OBD codes
Search Buick fault-code guides when you want the generic OBD-II definition with notes that are a little closer to common Buick fault patterns.
Showing 4 sample guides. Refresh to rotate the mix.
P0420
P0420 usually means the catalytic converter efficiency is below the threshold the ECU expects.
Buick exhaust leaks, sensor bias, or a tired converter can all sit behind P0420.
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P0300
P0300 usually means the engine is detecting random or multiple-cylinder misfires.
On many Buick engines, ignition weakness, intake leaks, or airflow issues are common starting points.
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P0171
P0171 usually means bank 1 is running too lean.
On many Buick engines, intake leaks and airflow-side faults move high on the list for lean codes.
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P0174
P0174 usually means bank 2 is running too lean.
A vacuum leak, airflow sensor issue, or fuel-delivery problem is the first place to look.
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