P2198: O2 Sensor Signal Biased/Stuck Rich (Bank 2, Sensor 1)

What does P2198 mean?

P2198 is the bank 2 counterpart of P2196: the bank 2 front oxygen or A/F sensor reports rich in a way the ECM does not accept. On GM's Bosch-based 2005 2.8 and 3.6 V6 the bank 2 rear sensor must read lean (below 0.15 V) while the front sensor reads richer than lambda 0.92 and the short-term trim has dropped to its 0.75 minimum; the code then sets after about 100 s, or 50 s cumulatively, over two trips. Ford uses the same lack-of-switching, trim-limit and stuck-lambda logic as on bank 1, sets the stuck-rich code when the frozen lambda value is below 1, and suspends the stuck-rich test during cold starts while fuel boils off the oil through the crankcase ventilation. A sensor contaminated by oil or coolant, or one whose signal or reference wiring has a fault, gives this pattern; since the ECM leans bank 2 to follow the false reading, the rear sensor of that bank usually shows lean at the same time.

The code tells you which monitor failed, not which part is broken. Test before replacing parts.

Symptoms

• Malfunction indicator lamp on
• Possible hesitation or lean running

Common causes

• High Bank 2 front oxygen or A/F sensor contaminated or aged
• Low Sensor signal or reference wiring fault

Likelihood is a general estimate across vehicles; your make and model may differ.