Peugeot 307 XT 2002 catalyst anomaly

Hello again, this is the code that marks (PO420) and also marks this (po128) despite the fact that supposed mind is already new all thanks for your help thank you very much greetings

The P0128 indicates that the coolant temperature does not reach the necessary temperature to open the thermostat. Czech the temperature sensor, resistance, reference signal etc. You can take it out, connect a voltimeter placed in resistance and heat it with a hot air or seca-peppells pistol. Try to solve this problem first.
The P0420 refers to an inefficient cat. Compare the two Lambda sensors: the first must quickly fluctuate between 0.1 and 1 volt, thus detecting the amount of oxygen in the exhaust gases and reporting it to the ECU, so that the mixture is correct. The second sensor, the back of the CAT must be more or less stable, without large jumps, indicating the gases that leave the CAT were cleaned within it. If the second sensor values ​​resemble the first, then if the catalyst is failing. You can also check it with an infrared thermometer, the output temperature of the CAT must be about ~ 50 centigrades higher than the entrance if the cat operates in addition. If the input temperature is higher than the ELCAT output is not working. If the input and output temperature is (almost) the same, then the CAT is covered.
Finally: was the cat you put original or not?

Greetings