Driving home last night through the same village I drive through every night- clicked on auto speed limiter- nothing. Noticed there was no 30 mph sign on the dash. It's been there every other day. Any ideas? 

Do you have sat nav?

If the front camera didn't see the sign and it can't get it from navigation (not all roads have the speed registered on the maps), then it won't know what the speed limit is.

Yeah- my point is every day it's recognised the area is in a 30mph zone, 30 mph sign comes up on the dash. Last night, same village it didn't recognise it. 

Only needs a bit of glare on the sign, or the light to not quite pick up the sign and the camera won't see it.

Badly timed wiper, etc.

I get the same on mine, sometimes it just misses it.

Thanks. Me being stupid I guess- I presumed the speed limit information came from GPS, not the actual physical road sign. Cheers- every day's a school day! 

It uses both if you have sat nav, but it will prioritise the camera.

If it doesn't catch it on the camera and it's not in the maps though, then you get nothing.

I've noticed that although mine picks up and displays the sign posts, normally without error, eventually it "forgets" it has seen them.  If using Auto Speed Limiter and you don't notice you run the risk of inadvertently speeding.  I have also noticed that if I indicate right then left (ie, at a round about) even imeadiatley after it registers a speed sign, it then removes it from the display.  I went into the Traffic Sign page in the info diplay but instead of giving me the menu shown in the handbook I get "Traffic sign recognition Reduced peformance See manual"  Spookily there is nothing in the manual I can find that covers this.  Anybody seen this before?

Tried the auto limited last night for the first time (i use the manual limiter quite a bit, especially on motorway 50 zones, etc) but almost got rear ended when I was accelerating in a 50 zone and the camera saw a side road 20 speed sign!!! Initally thought my engine had given up on me until I overrode the limiter by flooring the pedal!... Not sure I'll be using that again.

Had a similar issue yesterday- on a roundabout in the middle of 2 "50" roads the car decided 30 was the limit which was emotional- not so keen on it now !