Technical Non working speedo JTD?

[rpc884]

Hi, I have a marea jtd 110hp 2001 and the speedo is intermitant in its operation, is this a common problem and is it likely to be the sensor mounted on the gearbox? When its not working it effects the engine management making it jerking to drive. Thanks

 

[stylers]

common enough, sensor could be faulty but also check the wiring and connector carefully, check for 12V and earth at the connector pins.