Audi Repair: A4 TDI FUEL GAUGE, fuel gauge, diagnostic check

Question
A4 Tdi 2001 y-reg(newer shape)fuel gauge moves very very little when ignition is switched on brand new sender and pump fitted,all needles sweep to full with diagnostic check. Bosch cluster part number 8EO 920 950 F  i can get hold of a cluster but part number ends with a letter C instead of letter F. Whats the difference?. is there a chip on the board i can change? i have a spare board.
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Answer
Hi
I live in US ,,, we don/t have TDI so don't know difference between C and F>?
There is a V/B (use VAG) where resistance can be checked
if it/s the same what's on sender at the connector, I will replace cluster
good luck                  pltech