This is the blue coolant temp 2 sensor for 1.9 and 2.1 water cooled T3 engine.
If you are having issues with poor running this is a simple fix and will often solve your problem.
This is a German quality brand part from Topran.
Fits: VW T3 Caravelle and Transporter from 1984 to 1992 with a 1.9 or 2.1 waterboxer engine.
Part Number: 025906041A