Code 33, Speed Sensor, Any Ideas?

[2087]

Hey, well my first post looking for help has come quickly!

I got a code flashin, and it showing code 33, vehicle speed sensor.

For some reason i got into car today and it wasnt on, but it did pop back on after givin it a bit of go juice.

Any ideas as to what to look at? what to check? I dont really know where to look lol.

The car isnt majorly modified, had a new tubby 15k miles ago, has a custom manifold and a decat'd powerflow exhaust system.

Dont know if any of that is likely to make any issues but let me know if anyone has any suggestions

Cheers