Check inspect 2012 speedo sending unit.

[Reiver]

No speedo ...the speedo has power and both the speedo and tach do the 'sweep' when the car is turned on.  It shows the mileage and is lit. 

However, no speed indicated when driving and no odo change so suspect the sender.

Jacked up, wheel off and properly adjusted to .625 mm from the wheel...the power on and the clear portion of the sender lights up where the wire enters the tube.  Spin the hub and it remains lit, does not pulse..... I am assuming it should?  Yes?  If so then toast.

[Origin7]

From my non-automotive/industrial experience, if these sensors have an LED they typically pulse ON/OFF when triggered. If you're sure a metal object is passing through the viewing area, and you're getting nothing out, it's toast.  

[Reiver]

That was my assumption but wanted to ask..... easy to fix with the replacement... the newer ones are supposedly more stout.

[mccasksl]

FWIW / YRMV (ref: 2008 S3 Duratec) I went thru a similar iteration, replacing the sensor after the speedo started acting erratic and then quit altogether. Still no go with a new sensor with the gap set at 0.8mm (my 2007 assembly guide (supplied w/ the car) says 1.0mm gap, more recent guides Duratec 2.0 on say 0.8-0.9mm gap). After reading trials and tribulations of others on the Caterham and Lotus Seven Club site (one report of reducing the gap to 0.5mm to get it right), I started reducing the gap and at 0.45-0.5mm (0.020") or so (best I can measure, looks tight) it now works perfectly. I never was able to see the fiber optic light thru the small hole in the side of the sensor, lite or not. I wonder if my original sensor was fine all along with the gap just out of wack. You might try adjusting the gap before purchasing a new sensor. 

Cheers!

Steve

[Reiver]

Thanks.... I'll give that a shot as razor thin as I can get it without touching.... but I do have a new one enroute

[CBuff]

Mine started acting up last year. Tweaked the gap spacing and it worked as intended.  The light does pulse when you rotate the hub and the reluctor wheel passes by sensor. One attempt had it reading well at low speed but above 60-70 it would act erratic.  Small tweak to gap fix this. (2023 420r) 

 

https://www.caterhamlotus7.club/forums/topic/257730-speedo-sensor-replace/