Code Definition

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

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

About P1187

P1187 is a manufacturer-specific powertrain diagnostic trouble code recorded for Volkswagen 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, sensor 1, is the primary feedback device for closed loop fuel control, telling the Engine Control Module (ECM) whether the exhaust gas leaving the engine is rich or lean so that fuelling can be corrected in real time. On a wideband sensor this involves several separate circuits, a pump current line, a Nernst cell line, a reference voltage line and a heater supply and ground, all carried in one lead and one connector. DTC P1187 is a general circuit fault for sensor 1, meaning the ECM has detected an electrical problem in the sensor circuit that does not fall n...

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