Code Definition

P1187 — Heated Oxygen Sensor 1 bank 1 or 2 circuit fault

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

About P1187

P1187 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 P1187 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.

P1187 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, designated sensor 1, sits ahead of the catalytic converter and gives the Engine Control Module (ECM) the feedback it needs to hold the air fuel ratio at target under closed loop control. On these applications the sensor is a heated unit, and depending on the engine it may be a switching sensor or a wideband type carrying a pump cell, a Nernst cell, a reference line and a heater. DTC P1187 is stored when the ECM detects an electrical fault in the sensor 1 circuit, and the definition covers either bank, so the first job is to establish which bank the fault has ...

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