I've suspected mine under reads the temp for a while now and this weekend I'm going to test it against a known good thermometer. 2012 TDV8 Vogue (L322)

The outside temperature sensors are not exactly scientific instruments and are rarely completely accurate . Ok when moving in clear airflow . Not accurate in slow traffic or stop start driving due to heat soak from a hot engine or even hot brakes . Might need a clean if it’s under reading .

Had a quick look at the external temp sensor behind the grill but there's nothing much to see, I think its working fine as it shows a fairly accurate temperature on the dash and in diagnostics.

Thanks for the suggestion all the same though!

I'm waiting on a replacement BCM to try (it bugs me that it's output to the servotronic is not shown in SDD/Autel)

It was posted on Wednesday by tracked 24 but still no sign of it, as is to be expected with RM at this time of year.

The new BCM finally arrived yesterday, I've quickly fitted it this morning on my way out.

Sadly it's not the smoking gun I was hoping it could have been.

Even with the replacement BCM diagnostics still states the output to the servotronic is 0v and 0% PWM even though I know this isn't true as both the original and replacement BCMs read 7v output on the servotronic wires so they do at least do something.

Click image to enlarge

Sorry that last line should have said:

Does anyone know how to measure the speed signal coming in to the BCM? (From the ABS/instrument cluster?)