Advice ref: Engine Warning Light ? O2 sensor
 

RX8 231 2004 Plate
2 weeks ago engine started misfiring, no power and yellow engine warning light stareted flashing. Pulled over, engine stalled. Popped bonnet and saw smoke from rear bottom of engine on Washer bottle side. Called AA. Car wouldn't restart. Taken to Mazda dealer. One of the Coil packs had shorted. Both replaced. Engine started first time. Tested OK. Exhaust gases checked OK.
On trip back from London to S Wales, yellow engine light came on constant. Engine running A OK. According to manual this light indicates either, Low Fuel, electrical fault or problems with emission control.
Engine running fine, no problems. All electrical systems OK and 1/2 tank fuel. My question - Could the O2 sensor be damaged from the previous problem when neat fuel was being exhausted into the Cat Converter. The emissions checked Ok at that time and the mechanic mentioned that the o2 sensor seemed OK.

At present car is running perfectly except for this continuous light.

Get the code read and let us know what it comes back with.
We can only speculate many possibilities at this point.

Agreed. Could be O2 sensor or clogged cat.

Update.
 

Well, it seems it was a ghost warning. According to diagnostics the engine was running too lean. Exhaust gas analysis showed the emissions were spot on "Normal". Checks of all other systems were nominal. Therefore the ECU was reset to default and the warning light reset. Once again exhaust emissions were OK. Engine running well. Have covered 200+ miles since. Will see what the future holds, but there doesn't seem to be any problems. :)

Good news. Go forth and rev!!