Hummer check engine codes

Overview

Hummer H2 and H3 models used GM engines. Codes follow GM truck patterns.

Codes notably common on Hummer

• P0171 System Too Lean (Bank 1)
• P0455 Evaporative Emission System Large Leak Detected

Hummer specific notes

• Use GM style diagnostics: intake leaks, MAF sensor cleaning, and EVAP vent valves.

Owner's manuals

Official Hummer owner's manual / owner portal (manufacturer site; we do not host copies).

Recall lookup

Check open Hummer recalls with your VIN at the NHTSA recall lookup.

Sources

• https://www.nhtsa.gov/recalls

Sources checked October 2026. Bulletins apply only to the models and years they list.

All other codes

These work the same on Hummer as on any vehicle:

P0420 P0430 P0300 P0301 P0302 P0303 P0304 P0174 P0440 P0442 P0456 P0128 P0135 P0141 P0101 P0299 P2135 P0401