Code Definition

P2177 — System Too Lean Off Idle, Bank 1

System: Powertrain  |  Type: Generic (OBD-II Standard)  |  Make: Generic

About P2177

P2177 is a generic (obd-ii standard) powertrain diagnostic trouble code. It belongs to the P-prefix family of codes, which covers engine, transmission, emissions, or fuel-system faults.

When P2177 is stored, the module has detected a bank-specific fault, meaning it applies only to one cylinder bank of a multi-bank engine.

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.

Because P2177 is a generic OBD-II code, its base definition is shared across manufacturers. The specific diagnostic steps, reference values, and repair procedures can vary by vehicle, and the TaT Diagnostic Assistant includes verified procedures submitted by working technicians.

Code Information

The Engine Control Module (ECM) continuously monitors air to fuel mixture correction using oxygen sensor feedback during off idle and light load operating conditions. DTC P2177 is set when the ECM determines that long term and short term fuel trim corrections for Bank 1 exceed the calibrated lean threshold while the engine is operating above idle speed, indicating that the commanded fuel delivery is insufficient to maintain the target air to fuel ratio under these conditions. The ECM responds to a lean condition by increasing injector pulse width via short term fuel trim, and when the offset p...

Join TaT to view the complete code information and diagnostic details.

Quick Facts