If your only getting a 1.2 ohms the sender could be bad.,.. most vdo 120c (250C) temperature senders have a resistance of 287ohm to 22.7ohm.... but it's also imortant to check the wiring/ ground on the gauge to eliminate possible sources of problems.
refernece for testing senders. One of the links I posted earlier had ohm ranges for the senders asreference;
How to Troubleshoot VDO Sending Units- by Quinten Plummer-
VDO produces a third-party line of automotive gauges, ranging from temperature gauges to pressure gauges. VDO sending units monitor your automobile's components and processes and then report this information to your automobile's gauges. If you start to notice odd readings on your gauges, your automobile's components may not be at fault -- there may be a problem with your VDO senders.
1 Test a VDO temperature sender using a multimeter. Switch the multimeter to "Ohms." Touch the temperature sender with the multimeter positive lead, or clamp the positive lead to the sender. Touch or clamp the multimeter black lead to a solid metal portion of your car. The temperature sender ( at room temperature) should register 700 Ohms - 287 Ohm ( spending on sender model) when cold, and 22 Ohms after the car has warmed up.
2 Test the Ohm output of a VDO pressure sender using a multimeter. -- Set the multimeter to "Ohms." Touch or clamp the multimeter black lead to a solid metal portion of the car. Touch the sender with the multimeter positive lead. The sender should register 10 Ohms with the engine off. Start the engine and test the pressure sender again. For engines with 40 psi oil pumps, the sender should register 105 Ohms. It should register 152 Ohms for engines with 60 psi oil pumps.
3 Test your VDO fuel sender with a multimeter. Disconnect the fuel sender positive wire from the fuel gauge; disconnect the negative wire. Touch the negative lead of the multimeter to the negative wire and the positive lead to the positive wire. The fuel sender should show between 10 and 180 Ohms, depending on how much fuel is in the tank. It should register 10 Ohms on a full tank and 180 Ohms on a full tank. If your fuel level falls between full and empty, the Ohm output should register between 10 and 180 Ohms.
Also, it's much easier to work on the gauges if you push them out of their sockets... from behind just push gently... the rubber gasket will release wth the right amount of pushing. They will dangle from the cables through the hole, but enough for you to see, work and test all connections...
if your car is a VS I can send you their wiring diagram they sent me when they built the car... but always best to make your own, as not all cars are consistent. The files i have are PDF... I can email, but don't know how to post PDF files on the site.