P0606 Code After O2 Sensors replace

Greetings,

2007 Tacoma 4.0 V6

I got a P0606 Fault After O2 Sensors replaced. I replaced the upstream with Bosh 15996 and down stream with the appropriate Denso's. I had an intermittent check engine light prior to the new sensors but was never able to get a scan on it in time before it shut off and was getting poor mileage. I ruled out all other poor mileage causes prior to replace O2 sensors which seemed to work but now P0606 code...any ideas I have reset the PCM after new sensors were installed by battery disconnection.