What port are you pulling that from? Im assuming A2, but here is what 212 means on all the ports that can pull a 212.
A1 S2 solenoid short circuit to battery
A2 its an o2 code (they dont like off brand o2 sensors, id replace it with bosch)
A3 Right front wheel sensor, no signal on moving off
B1 Driver’s side damper motor position sensor shorted to earth
B2 Malfunction in the circuit to the vacuum pump or regulator
B5 Drivers airbag open circuit
As stated the A2 is my guess that your referring to, check the wiring and make sure everything is seated correctly, NO DiElectric grease and when all else fails replace it with a bosch sensor these cars hate aftermarket sensors