P241A O2 Sensor Signals Swapped (Bank 1 Sensor 1 / Bank 1 Sensor 2)

With P241A the engine controller has concluded that the oxygen readings of the sensor ahead of the bank 1 catalyst and of the sensor behind it fit the opposite mounting positions, so the two plugs or harness legs are most likely crossed. FCA uses the code on the 2011 Ram 2500/3500 with the 6.7L Cummins diesel and calls it an oxygen concentration mismatch between sensors 1/1 and 1/2; bulletin 18-012-12 Rev. A brings revised ECM software for it among other faults. CARB requires every sensor used for fuel control and catalyst checks to be monitored. P241B is the bank 2 pair, P2416 the pair behind the catalyst. In practice the code follows a sensor or exhaust repair; mixture control and catalyst diagnosis then work with wrong data.

Likely causes

Symptoms

• Check engine light after work on the exhaust or the oxygen sensors
• Mixture adaptation drifts, fuel trims look implausible
• Catalyst or sensor codes set as follow-up faults

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.