P0040 - O2 Sensor Signals Swapped (Bank 1 Sensor 1/Bank 2 Sensor 1 )

System Information

O2 sensors are used to monitor the Oxygen content in the exhaust system, there will normally be a sensor before the catalyst (sensor 1) and one after the catalyst (sensor 2)

Fault Code Explained

the PCM has detected that the signals for the two sensors are the wrong way round. This fault is most likely due to the multi plugs being connected incorrectly.

Recommended Tests

Check and swap multiplugs for the two affected sensors