lake and air temp reading

[Nutriscitoo]

I've got an 05 Sportster.  My question is about the reading of the lake and air temp on the speedometer.  They read in the 20's and the manual says the readings are in Fahrenheit and not adjustable.  Does any on know where the sensors are or has anyone had a similar problem and found a fix.  My analog tach also is not functioning.  I read a lot of trouble shooting tips about it, but have seen nothing on the other temp sensors.  

[electricjohn]

Air temp sensor is in the engine room air intake opening under the windscreen, drivers side.  Water is built into the bottom of the hull.  The 20's readings may be failure default readings.  Not sure though.