I have checked for vacuum leaks, and still have the dreaded heat code on the O2 sensor. Is it a pretty sure thing?
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Obama, One and Done!

I believe that code is referring to the pre-heater circuit part of the forward sensor, rather than the actual oxygen sensor portion. That's what happened on my 03 V70 NA (but aft sensor in my case).

Try this: Clear the code. Then turn the ignition on for about ten seconds but don't start the engine, and turn the ignition back off. Then connect the scanner and check to see if the code P0032 re-asserted itself. If it did, then the problem most likely lies in the pre-heater portion of the sensor, since you didn't actually run the engine which would be needed in order to get an actual oxygen level error.

Okay, I put the car into the run position, cleared the code, and turned it off. Rechecked the OBD II and there was no code. Restarted the engine and code was back. No check engine light though. Now what?
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Obama, One and Done!

"...Okay, I put the car into the run position, cleared the code, and turned it off..."

Let me try that again......

AFTER you've cleared the code and turned it off, turn the ignition back on again but DON'T start the engine. Leave just the ignition on for several seconds. The sensor pre-heater should be trying to work as long as the ignition is on, even though the engine isn't running. (At least that's what I seemed to observe.)

So after the ignition has been ON for several seconds WITHOUT the engine running, turn the ignition back OFF. Now connect your scanner, turn just the ignition ON and read the codes. Note, you never start the engine this whole time.

The only point I'm trying to make is that in my case, I was able to re-assert the pre-heater fault code without even starting the engine - just by turning on the ignition. I don't know what year, etc, your's is, but it might be that it doesn't power up the pre-heater until the engine is actually started. Also, in my case, the car ran perfectly fine. It just kept recording the fault code each time I turned the ignition on. A new sensor cured it.

It's really sounding to me like you need to R&R the sensor.

Okay,

I did as you said. There is no code present with the engine not running but the switch in the on position. As soon as I start the engine the code comes right back. I'm at a loss...........
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Obama, One and Done!

I saw in your other thread that you replaced the sensor and still have P0032. Is that correct? If so, I'm curious - did you replace it with an exact OEM plug-and-play (Denso brand) sensor?

http://www.amazon.com/Denso-234-9019-Oxygen-Sensor-Ratio/dp/B000C5WD6M/ref=au_pf_pfg_s?ie=UTF8&Make=Volvo%7C27&Model=V70%7C150&Year=2001%7C2001&carId=001&n=15684181&newCar=1&s=automotive&vehicleType=automotive

No, bought Bosch. Denso will be here tomorrow. Tried to do it on the cheap. Guess i'll never learn.
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Obama, One and Done!

I know how you feel. My frugality gets pretty expensive sometimes, not to mention the wasted time.

Good luck. Hope that cures it.

Got the Denso sensor this morning and installed it. No more codes.
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Obama, One and Done!

I am not sure if the preheater will turn on with the key, but it most certainly will when the engine starts.

Time for a new O2 sensor. Get one that plugs in directly, cheap sensors don't always work properly. Tasca Volvo comes to mind.
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My name is Klaus and I am a V♂lv♂holic

I'll give it a try and post back
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Obama, One and Done!