Code Definition

P1148 — Heated Oxygen Sensor 1 bank 2 too rich

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

About P1148

P1148 is a manufacturer-specific powertrain diagnostic trouble code recorded for Audi 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; and a sensor-related fault — the reported value from the named sensor is out of spec.

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

The upstream heated oxygen sensor on Bank 2, designated Sensor 1, measures the oxygen content of the exhaust ahead of the catalytic converter and feeds the Engine Control Module (ECM) closed loop fuel control. DTC P1148 is set when this sensor reports a persistently rich exhaust on Bank 2 and the ECM reaches the limit of its ability to remove fuel in response. The rich indication can be genuine, caused by excess fuel delivery or too little air, or false, caused by a contaminated or biased sensor reading high. When this code is stored the driver may notice a rich or rough idle, a fuel smell, so...

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