Code Definition

P1171 — Fuel mixture lean during acceleration

System: Powertrain  |  Type: Manufacturer-Specific  |  Make: Honda

About P1171

P1171 is a manufacturer-specific powertrain diagnostic trouble code recorded for Honda vehicles. It belongs to the P-prefix family of codes, which covers engine, transmission, emissions, or fuel-system faults.

Scanning & clearing: A generic OBD-II scan tool will usually read and clear powertrain (P) codes. For live data, freeze-frame capture, and bi-directional tests you may need a more capable scan tool that supports the vehicle's ECM protocol.

P1171 is a manufacturer-specific code. The same code string on a different make may have a different meaning. Always confirm the code's definition against the vehicle's service information for the specific make and model under test.

Code Information

DTC P1171 is a Honda specific code indicating the primary Air Fuel Ratio sensor has detected the mixture going lean during acceleration. Under acceleration the Powertrain Control Module (PCM) commands additional fuel for the extra air entering the engine, and it expects the air fuel ratio to stay close to or slightly richer than stoichiometric. P1171 sets when the sensor instead reports a lean mixture under load, which usually means the fuel system cannot keep up, air is entering unmetered, or an air metering signal is reading low. The driver may notice hesitation, a stumble or flat spot on ac...

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