UK-POLOS.NET - THE VW Polo Forum

The mirror heating is not working and there are no error codes. The temperatures are sub zero, I'm not really sure what the problem may be...

On a 9n3 I bought I had the same issue and had 2 causes.

1. The mirror glass had been re-attached to the heating element with double-sided tape by the previous owner. £63 each from VW
2. The coding for activation time had it set to turn off after 30 seconds and every time I changed it the module would reset the value after an ignition cycle back to 30 seconds

If a fuse had blown I'm not sure if you'd get a no com or open circuit error as I believe the heating elements just have a positive and a negative, no monitoring. Unless the BCM is monitoring the output to the mirror heating elements, I'm not sure.

Do you hear a relay click on and off when you turn the mirror heaters on and off?

If not probably worth quickly checking fuses and popping the glass out to see if the connectors for the heating element are full of corrosion or corroded off/loose.

The fuse was the first thing I checked. i don't know if there is a relay clicking when turning them on. I'll listen to it next time i go on a drive and if its not working I'll take the glass off

I've burned out the heaters on both sides of my previous car a 2000 VW Passat 4Motion, it was easy to do that on that year of car as the heaters stayed on for as long as you have the switch in the ON position, something that I did not know about until I read about it on an American Passat forum, which, unfortunately was too late for me!

There were no fault codes logged although both sides were burned out, this is due to the fact that when the heater tapes burn out, the surface below them burns as well - and carbon conducts! It was only when I removed the wires to each side that fault codes were logged, so it sounds like the monitoring system has or had, at that age of car, too low a minimum current value for "okay".

There should be a lot more protection for these on this model/age of car, I've accidentally left them switched on at times - without causing them to burn out, without knowing what the coded "on" time for them is.

On the polo I thought they only turned on when the temp is under 4 Celsius

On 6R the BCM J519 manages the operation of the heated exterior mirrors, it is supplied by a +30 signal from the SB24 fuse.

There is a possibility that this management is 'Automatic', they should work as soon as you hear the 'ding' on the instrument panel when it shows the ice symbol.

I seem to remember that some combination of Bits 2 and 3 disables the knob switch signal for heated exterior mirrors.
If the function is via CAN, with subzero temperatures they should work.

I think i enabled bit 3, I'll try to turn on the rear windows heater and check if the mirror heating turns on

Well I turned the rear window heater on and the mirror heating started to work. Would've never in 1000 years guess that that was the problem . Thanks a lot.

The obvious way to have the mirror heating controlled is via the heated rear screen, also most mirror heating is required for demisting purposes and not just de icing.

The face lifted version of 6R Polo, ie the 6C, at least for UK market, has the heated mirror enabled with just its switch on and the engine running, no heated rear screen also on required.

I do agree though that most of the time, at least for my wife and I, is to use the mirror heaters to de-mist the mirror glass, typically after driving out of a cold garage in the morning where the temperature has risen over night, and also, like today, where the air temperature has risen while parked up.

I sure that our last Polo, a 2002 model's heated mirrors worked the same way, I'd have to go back to 1991 to have had a car, a VX Cav GSI 4X4, that needed the timed heated rear screen heater on to be able to power up the heated mirrors.

RUM4MO wrote: Sat Dec 24, 2022 12:31 pm The face lifted version of 6R Polo, ie the 6C, at least for UK market, has the heated mirror enabled with just its switch on and the engine running, no heated rear screen also on required.

I do agree though that most of the time, at least for my wife and I, is to use the mirror heaters to de-mist the mirror glass, typically after driving out of a cold garage in the morning where the temperature has risen over night, and also, like today, where the air temperature has risen while parked up.

I sure that our last Polo, a 2002 model's heated mirrors worked the same way, I'd have to go back to 1991 to have had a car, a VX Cav GSI 4X4, that needed the timed heated rear screen heater on to be able to power up the heated mirrors.

Having looked at a few 6Rs it seems that some of them don't have the rotary switch above the lock and unlock button on the driver's door handle for mirror adjustment, heating, and power-folding? I'm assuming that they'd then have manual adjustment and the heating would be switched on or off with the heated rear window.

Bepis wrote: Sat Dec 24, 2022 8:28 pm Having looked at a few 6Rs it seems that some of them don't have the rotary switch above the lock and unlock button on the driver's door handle for mirror adjustment, heating, and power-folding? I'm assuming that they'd then have manual adjustment and the heating would be switched on or off with the heated rear window.

Remember that a lot of Polos will not have heated mirrors, and more will not have power folding mirrors.

Silly question, should there be heaters on both sides? I'm not sure the passenger side is clearing.

Polo Driver wrote: Tue Dec 27, 2022 7:36 pm Silly question, should there be heaters on both sides? I'm not sure the passenger side is clearing.

Yeah both sides should be heated

johntheo2 wrote: Sat Dec 24, 2022 8:05 am The obvious way to have the mirror heating controlled is via the heated rear screen, also most mirror heating is required for demisting purposes and not just de icing.

Yes, totally agree.
Mirror demisting is also necessary, especially when going through valleys with high humidity... the temperatures do the rest so that the exterior mirrors end up fogged or with drops that make good vision impossible.
Besides, if you practice sports inside the car , most of the time you will need to defog the rear window, but not the heated exterior mirrors.

Those were 'my' reasons for not activating any of the bytes (2 and 3, see my previous post) for an automatic operation, ... since the knob switch is left disabled.