P2198 indicates that the upstream oxygen sensor on bank 2 (sensor 1) is reporting a continuously rich condition — its voltage remains high instead of cycling normally. The code is set when the powertrain control module detects a biased or stuck‑rich signal from that sensor.
The sensor element or its internal heater can fail, causing the output voltage to stay high (rich) regardless of actual exhaust composition.
Open circuits, short‑to‑ground, or corroded pins can bias the sensor signal toward a rich reading.
A leak before the sensor allows outside air to enter, which the sensor interprets as a rich condition.
Leaking fuel injector, high fuel pressure, or a faulty fuel pressure regulator can make the mixture genuinely rich, causing the sensor to report correctly but triggering the code.
A defective PCM can misinterpret a normal sensor signal as biased rich; this is rare and should be considered only after all other causes are eliminated.
No. The PCM is rarely the cause. Most often the upstream O₂ sensor, its wiring, or an exhaust leak is responsible. Replace the PCM only after all other possibilities have been ruled out.
A failing catalytic converter typically sets downstream sensor codes (e.g., P0420). It does not directly cause an upstream sensor to read stuck rich.
The vehicle can be driven, but fuel economy will suffer and emissions will increase. Prolonged rich operation can damage the catalytic converter, so repair should be scheduled promptly.
Bank 2 is the cylinder bank opposite the one containing cylinder 1 (on V‑type engines). Sensor 1 is the upstream (pre‑catalyst) oxygen sensor on that bank.