All Q7 with TDI engines (3.0 and 4.2) have an auxialiary heater factory fitted.
The difference between the aux heater and the parking heater is that the second one has 3 extra items:
1. Shut-Off Valve N279 is fitted. This valve is actuated by the Aux Heat Control Unit and it closes the long coolant circuit. In this case when the Parking Heater is turned ON (by MMI timer or by remote control) it closes the long coolant circuit (engine) and circulates the coolant only in the short circuit (passenger compartment). Without this valve fitted during cold winter days, it takes a very long time to warm the passenger compartment as the coolant is circulated also thru entire engine.
2. Remote control receiver. This is fitted in the luggage compartment on the right hand side, next to the Phone Aerial Amplifier. It is used to receive the commands from the remote control and to turn the aux.heater on/off. It is connected to 12v, with only one wire to the aux heat controller and to the antenna amplifier in the right C-Pillar. Not all Q7 though have the right antenna amplifier that has the output for heater remote control. All of them have the antenna fitted on the right side window.
3. The remote control which is a standard Telestart T90 unit. The remote control can be easily adapted to the aux heater control unit using Ch.4 under Adaptation.
To enable timers in the MMI it is very simple as long as the aux heater control unit is there.
To do this you have to check first with a Vag-Com interface if you can see and interogate the controller 18-Aux.Heat.
If YES then select controller 08-Auto HVAC (Climatronic control unit) and add 2048 to the actual coding. Save the coding and restart the Climatronic by turning ignition off and on again.
Now pressing the SETUP button on the Climatronic Control Unit (NOT THE ONE IN THE CENTER CONSOLE UNDER THE CAR BUTTON) you will see the timers menu active.
Using the Climatronic Setup you can turn Aux Heat ON/OFF, Ventilation ON/OFF and also program up to 3 timers for the Aux Heat.
Without the valve the Aux Heat works fine but you have to remember that it is taking longer to heat up the passenger compartment.
In october last year i have installed in my Q7 the Shut-Off Valve. I also bought from ebay the remote control receiver (is the same unit in a6, a8 and q7) and the original remote control and installed them. All are working very good and i used them a lot during winter.
The shut-off valve i bought it new from my German Audi Dealer and was about 100 Euros.
The Remote and the receiver were 200 Euros on ebay.
BTW, i have a receiver for sale that i bought for a friend of mine also from ebay but he sold the car and we never had the chance to install it.If anybody is interested drop me a PM.