Speedometer issue

[Blackshuck]

Getting an intermittent problem with the speedometer on my '04 2.0 hdi not working .
When it stops , the engine actually seems to run better for some reason - the vehicle seems to accelerate slightly & the engine seems to go quieter & run smoother .
Then the speedometer starts working again as normal .
What actually drives the speedometer - is it a sensor on the gearbox ?

[Sol]

Yep. Must be struggling for power if a slipping speedo drive makes it faster!

[oilyrag]

Speedo pick up takes the signal from the final drive. Trace the wires down to the sensor and look for any breaks/bad connections? I seem to remember 3 or 4 wires, all small diameter.
Good luck!