9 months ago one of the coil packs on my 2004 RX8 failed spectacularly, loss of power then stalled with smoke from bonnet and central console. Towed to local Mazda dealer. Both coil packs replaced and smoke probably due to fuel igniting in catalytic converter. Emmissions test OK when everything fixed. Car performed normally. 1 month later yellow engine warning light came on. Went to my local performance car garage that look after the car. Diagnostics indicated a Lamba sensor. I gather there are 2 such sensors, one on the cat and one, more difficult to change, on the manifold. Anyway diagnostics didn't indicate which one was faulty so we decided to change the one on the cat, the easy one, which cured the problem for 9 months. Now the same yellow light has come on twice but cleared itself. Diagnostics, the garage has new software, shows the following error message " p0420 - Needs a Lamba sensor Bank 1 Sensor 2 ".

Does anyone know which sensor this is?

 

P0420 Catalyst system efficiency below threshold ON 2 Catalyst ´
(See DTC P0420 )

http://www.themazdaforum.com/showthread.php?t=1516


you can just google the codes.