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

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.

Likely causes

Symptoms

• Malfunction indicator lamp on
• Possible hesitation or lean running

Repair estimate

Typical range across vehicles; the real cost depends on what the testing finds.

Parts involved

Related codes

References: fordservicecontent.com, gsi.ext.gm.com.