Multiple cam-related fault codes

[ChairmanRon]

Friends, I could use some help.

I'm suddenly receiving three fault codes on my 03 986. Durametric reports this:

P0346:
Porsche fault code 113 - Phase sensor 2 (camshaft Hall-effect sensor 2)

P0335:
Porsche fault code 110 - RPM input circuit

P0021:
Porsche fault code 325 - Camshaft position with respect to crankshaft bank 2

I have already replaced the RPM (Reference) sensor, to no avail.

The running condition appears OK, although I believe there is a slight power reduction when this intermittent problem occurs. There is no problem starting or operating otherwise.

Can someone suggest the cause and solution?

Many, many thanks.
Ron