Code Definition

P1198 — O2S Heater Circuit Bank 1 Sensor 2 Electrical Malfunction

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

About P1198

P1198 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 P1198 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.

P1198 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

Bank 1 sensor 2 is the post catalyst oxygen sensor, mounted downstream of the catalytic converter on the cylinder bank containing cylinder number 1, and its job is to monitor converter efficiency rather than to trim fuel directly. Sitting well down the exhaust it runs cooler than the upstream sensor, so its internal resistive heater is essential to bring the element to operating temperature and keep it there during idle and light load driving. The Engine Control Module supplies the heater with battery voltage through a fuse or oxygen sensor relay and switches the ground side with a pulse width...

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