A while back I ran across this interesting article on the engine coolant temperature gauge on the RAM ProMaster.  It basically says that the temperature gauage on the ProMaster starts out at the cold end, and progresses upward to about half way up the gauge range as the van warms up, andT then just sits there at the half way point pretty much whatever happens to the actual coolant temperature.  So, the gauge will get up to the half way point when the coolant temperature gets to about 160F and will just stay at the half way point even though the coolant temperature is actually fluctuating between 160F and about 220F (or maybe more).  They program it to  behave this way so as not to have to answer questions from owners about why the temperature varies so much.    Apparently many newer cars are set up this way.  Sort makes the temperature gaube useless.

After reading this, I decided to add a gauge that plugs into the car’s OBD2 port.  The gauge will show the actual coolant temperature as well as dozens of other car/engine parameters that are available from the OBD2 port.  I got one called the Ultra Gauge

Ultra Gauge OBD2 gauage

After installing the gauge, I went on a 10 mile drive and kept an eye on what the actual coolant temperature vs what the dashboard gauge showed…

I suppose that if you reach what the computer thinks is an actual harmful temperature it will move the gauge up the dial further — and probably give warnings on the info display.

The Ultra Gauge is quite a gadget…

Its very compact, but still easy to read.

I like the alarm feature, and have used to set alarms on coolant temperature and also to alarm when the fuel tank gets below about 6 gallons.  The user manual (a download from their site) is about 70 pages and quite detailed.

There are a number of competing ODB2 gauge competitors, so shop around.

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