DG.DG

Trying to diagnose this intermittent Check Engine Light. The error code from the Durametric is 0421 Catalytic converter, bank 1 below threshold +0420 same for bank2

This seems only to happen when driving with very slow accelerations, like accelerating like a typical car. Coupled with speed limit driving, 60 mph on freeway.

Is this really caused by the cats not reaching operating temp quick enough? What a perfect excuse.

This has happened about three times over the first year owning the car. The most recent time after a leisurely Sunday drive. This time didn't try to clear the error with the Durametric and after three or four more typical drives the error cleared on its own.

There are not a lot of details online about solutions. The two most common are replacing the O2 sensors and second replacing the CATs. Sensor replacement seems hit or miss. $2.5k plus installation for new Cats is steep.

2010 997.2 C4S Cab, 95k miles, uses less that half quart of oil in 5k miles.

Screen shot of Durametric O2 sensors that had errors, seemed to be operating in correct range.

voiceprint1

Do you have issue with smog check? 95k miles is pretty high for any make of car, so things will need to be addressed.

Petza914

You might be able to use an O2 sensor spacer to make the sensor a bit less sensitive and prevent the CEL. Or L, as you've noted, just drive the car as Porsche intended all the time.