Corsa Speedometer sensor

[Richodee]

I had two new tyres fitted, with no problems. However, I set off on a journey, and after 20 miles, the speedometer suddenly dropped to zero, then bouced back up to 70, then began to bounce up and down for about 20 miles. I lost no power, the car worked fine, but the speedo then died altogether. At the same time, the warning light on the dashboard lit ti say there was a fault in the engine electronics. The mileometer and the resettable mileage register also stopped working. I took the car to a garage, and they ran diagnostics, and told me the speed sensor on the gearbox was the fault. Could it have been the tyre fitters who have loosened something whilst fitting the tyres? How do I find this sensor to see if it is loose?

[burnhal]

Its unlikely a tyre change has caused this. Howver my first thought was speedo cable. Have a look here....

http://www.ilexa.co.uk/forum/index.php?board=1 1;action=display;threadid=2787

[woodchopper]

The speed sensor is located on the rear of the transmission casing above the left hand drive shaft.
One bolt holds it on so is easy to replace.
The reason everything else doesn't work is that it needs this sensor to be able to work out speed/mileage etc.