2006 XC70 does leaving accessories on when starting engine causes the checked engine light to go on?

Disconnect the battery for a few minutes and see what happens-continues to comeback have the Evap system checked out-

Here is a description for the fault code.

He engine control module (ECM) checks power consumption on the leak diagnostic unit pump.
A diagnostic trouble code is stored if the current consumption of the pump in the leak diagnostic unit varies too much during the reference phase.
The diagnostic trouble code (DTC) can be diagnosed when the leak diagnostic system is run.
For further information about leak diagnostics, see VIDA Design and Function.

Substitute value
The leak diagnostic is disabled.

Possible source
Contact resistance in the terminals
Blocked hose between the filter and the leak diagnostic unit
Damaged leak diagnostic unit.
Fault symptom[s]
Malfunction indicator lamp (MIL) lit.

The first thing you would need to do is have the engine control module software updated if one is available. For the most part that should take care of the problem. After the software update the evap test needs to be run to verify it took care of the problem. The evap test and software you should be able to get done for free at your Volvo dealership under the Volvo service for life program.

Call your local dealership to verify they are participating. Here is what you should get for free. A free scan for fault codes. The ECM software itself should have a 10 year/150k mile emissions warranty so you should not pay for it. To verify you do fall under that warranty have the service writer run your VIN# to confirm it does. If your engine control module does need the software updated then that needs to be done first. Once they update your software they can run the evap test That should be done under the free diagnostic. If the test passes then you are done and problem fixed. If you fail the test then more diagnostic needs to be done. At this point the dealership will ask you first if it is ok to proceed for instance a smoke test of the evap system and will cost "X" amount to continue. At that point you can give the ok or just say thank you very much but I will just take my vehicle now. For the most part the software will take care of it, or the leak detection pump has now failed. But if it is the leak detection pump you may want to see if the emissions warranty still covers that component or not? If your emissions decal says PZEV (Partial Zero Emissions Vehicles) then the leak detection pump has a 15year/150k mile emissions warranty coverage. Good luck to you and keep us posted. Also call Volvo of North America if you need to ask about the warranty coverage's.