I recently had to replaced a failed pre cat (under warranty-8yrs)on my E320 W210 1999.

As the pre-cat failed and started to rattle, the check engine light came on.

The code was reset during the repair by the MB dealer but the check engine light keep coming back.

Now the 2 of the 4 O2 sensors (both codes are for after cat sensor) have a code! The code refers to the sensor heater.

Can the rattling cat insert damage or contaminate the O2 sensor heater?

If so , can it be cleaned?

Can I reset the code myself on a 99 E320?

Regards