Fuel Temp Sensor HERE'S A RELIABLE, CHEAP AND EASY FUEL TEMP SENSOR In an SVO system, the fuel temperature is important, so here's a great little fuel temp sensor. The temperature sending unit on a VW is small enough to fit in the head of a bolt. The threads are a metric 10 M 1. It only cost me $10 new. If you are going to salvage one, only 1981 and newer had a temp guage. The machine shop tapped several bolts for free when they heard what I was working on. I use the factory guage and switch between fuel temp and engine temp. I intend to salvage another VW temp guage and get it mounted. HERE IT IS ON THE ENGINE It's more accurate when it's insulated. The other arrow points to the connection for the VACUUM GUAGE. This guage tells you if lines or filters are clogged or are beginning to clog. It actually allows you to monitor many things. It won't work on many diesels like Mercedes (at least I haven't figured out how yet). I concider it to be manditory for VW diesel/SVO conversions.