P241B O2 Sensor Signals Swapped (Bank 2 Sensor 1 / Bank 2 Sensor 2)

P241B concerns only engines with a second exhaust bank, typically V engines: the controller has decided that the front and rear oxygen sensors of bank 2 deliver signals that belong to each other's position. No manufacturer bulletin names P241B publicly; the only published use of this check found is FCA's bank 1 version P241A on the inline-six Cummins, where it is described as an oxygen concentration mismatch. A frequent variant on V engines is not a swap within bank 2 at all, but a sensor plugged into the bank 1 harness, which is why P241A and P0041 deserve a look as well. CARB sets the monitoring duty for oxygen sensors. Until the wiring is right, fuel control and catalyst testing of bank 2 cannot be trusted.

Likely causes

Symptoms

• Check engine light shortly after work on bank 2
• Bank 2 fuel trims or catalyst monitor results implausible

Repair estimate

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

Parts involved

Related codes

References: law.cornell.edu, static.nhtsa.gov.