The cat is clearly hot enough to work as your emissions are nice and low, so I would expect the lambda to be hot enough too.
The lambda do have a heating element which shoud get them in the working range before the catalyst.
Lambda can be a bit of a consumable I'm afraid.
It will be the front (expensive one) if it has failed as the rear one is just there to check the efficiency of catalyst and only compares to what it reads from the front lambda.
There is a possibility there is an air leak somewhere, perhaps in the exhaust, as your lambda reading is very high which means it reads a lean mixture.
If it were as lean as it's reporting it wouldn't be running.
It should be running Lambda 1, which = 14.7AFR
Your reading is Lambda 2.9 !!, which = 42.6AFR !!!!!
They start to run lumpy at idle around 15.2AFR, so your well away from even running if that's a true figure !!!!!
P.S The Lambda sensor is nothing more then a kind of battery cell that generates voltage based on oxygen content. When it sniffs oxygen it generates a small voltage from a chemical reaction. This voltage is normally 0.5-1V during the ECU control of the fuel mixture. A car running a closed loop 14.7AFR fuel target normally oscillates between 0.5V and 1V.
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