Engine Management Light intermittent.

[Wheelspinner]

I have an E86 3.0Si,every now and then it throws an engine management light,code reader says bank1 sensor 2, the sensor after the cat. Sensor is new and MTek tested the sensor and wiring on Fridayand it was ok,they did a smoke test and there are no leaks.Did some live data reads on my simple scanner,values look within tolerance when the light comes on,Seems to occur when i have been driving it hard and then do some slower driving. It does have a gravity style exhaust with a box delete after the cat. Bit of a puzzle can anyone help.

 

[Mike6]

Could it be the exhaust joint where it meets the manifold, very close to the sensor. If there is an air leak I understand this can affect the sensor throughing a code