Is the heater element separate to the o2 sensor or is it the same thing?

also should i take it too an offical dealership and pay $150 to diagnose, or should I just go ahead and replace the o2 sensor from my personal mechanic who will charge me $400 for the whole job.

THanks

Hi All, I have a 1999 Volvo S70 AWD Turbo that I just bought. The car has its check engine light on and is shooting out the following codes: P0036 (HO2S Heater Control Circuit Bank 1 Sensor 2), P0135 (Bank 1, Sensor 2), P0014 Exaust Camshaft Position Timing. When the car idles it throughs out a lot ...