Code Definition

P1148 — Closed Loop right hand bank 1

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

About P1148

P1148 is a manufacturer-specific powertrain diagnostic trouble code recorded for Nissan vehicles. It belongs to the P-prefix family of codes, which covers engine, transmission, emissions, or fuel-system faults.

When P1148 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.

P1148 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

Closed loop fuel control is the mode where the ECM continuously trims injection using feedback from the front heated oxygen sensor to hold the air fuel ratio near stoichiometric. DTC P1148 indicates a closed loop control fault on bank 1, the right hand bank, meaning the ECM is unable to enter or maintain closed loop control on that bank. This most often happens because the front oxygen sensor is not switching, is too slow, or is stuck, so the ECM has no usable feedback and stays in open loop. Causes include a failed or unheated front sensor, sensor wiring faults, or large air or fuel faults th...

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