C5 suspension error - garage say sensor?

[daleman 2003 c5]

Help? 2003 Citroen C5 2.0 Hdi 110hp VTR - 81,000 miles. lovely ride owned 18 years, would hurt to get rid of or scrap.
Getting intermittent Serious suspension error intermittently. Garage advise its a sensor issue in the gearbox but they can't get the part. Cleaned sensor but to no avail.
Diagnostics 3 instrument panel errors (DTC's) all - 0720 for vehicle speed , coolant Temp and engine speed - incorrect value received.
Started about a month ago, came on and then went off; Suspension ride seemed ok especially on uneven Lincolnshire dyke roads.
Since in Garage suspension now seem to be set up higher, but ride is still ok.
Error now when key inserted and on starting engine, but then go off and seems ok.
Driven over 150 since error first flashed up, but it always goes away

Garage says would still pass MOT in Nov, but am I doing further damage

[mickthemaverick]

What did the garage do to raise the ride height?

[daleman 2003 c5]

They advised that other than running diagnostic checks, clearing errors and retesting and take it for numerous drive to test that they didn't nothing else. It maybe just because I use to driving it that it now seems like a SUV drive with the front end slightly higher

[PaulC5]

The car should look level on the road, if higher at one end there is something not right.
Possibly the pivots on the height sensors on the anti roll bars need greasing or spraying - if doing this make sure you put the car on axle stands before going underneath.

[xantia_v6]

Do you know which sensor in the gearbox is (allegedly) faulty? Which model of gearbox? Manual/automatic how many gears?