P0041 O2 Sensor Signals Swapped Bank 1 Sensor 2/Bank 2 Sensor 2

On engines with two exhaust banks, the control module checks whether the downstream oxygen sensors are assigned to the right bank. It changes the mixture on one bank only, actively or as part of normal bank-wise control, and watches which sensor responds. If the sensor that should sit on the other bank reacts, the signals are swapped. This logic is documented for the manufacturer-specific predecessor codes; the usual cause is connectors plugged in crosswise after a repair. Behind the catalytic converters the response is slower, so detection takes longer.

Likely causes

Symptoms

• Check engine light on
• Catalyst efficiency code possible

Repair estimate

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

Parts involved

Related codes

References: v8sho.com, law.cornell.edu, en.wikipedia.org.