Suzuki Club UK

Hello had engine check light come on today, all seams to be running as usual. Idle fluctuates on warm up seams a little sluggish 5th gear is basically redundant and its kaining through fuel. How its been since ive owned it (2-3 months).
It shows code 24 as possible problem with vehicle speed sensor or speedo cable faulty.. As the speedo is working fine i guess its not that!
Could someone please point out where the engine speed sensor is? I imagine this could be a likely cause of my rubbish mpg?
Any help/advice is much appreshiated cheers

Speed Sensor on my Corsa was on the hub, but i Dont think it is on the suzuki. Will most likely be that, might even be on the gearbox!

Speed sensor as in mph? if so its on the t/box