Question? My 1995 SL320 has developed an erratic dash engine coolant temperature gauge. After warming up the gauge reads normal, then after a few minutes the gauge jumps to extreme hot then after a few minutes it reads normal again. This erratic gauge behavior repeats about every 5 minutes. So, I replaced the engine coolant temperature sensor (a single electrical pin sensor) that's screwed into the thermostat housing. Then I replaced the thermostat and the coolant recovery tank pressure cap. No change in gauge erratic behavior. Now I'm thinking I should replace the second engine coolant temperature sensor (it's a 4 pin electrical connection) which is also screwed into the thermostat housing right next to the one I replaced. However I can't seem to find anyone or anyplace that will provide me with the exact OE replacement sensor for my VIN number WDBFA63E7SF124282 Plus, I'm not sure if this car has two of these sensors and where would the second one (maybe the second one is for the fuel injection calibration???) be located and which of these sensors sends the signal to the actual gauge. No dash alarm or check engine lights are on so my guess is the engine is not overheating. So, I really don't know what or why is causing the erratic gauge behavior but obviously it needs proper diagnosis and repair. And no, I don't have any confidence in the local MB dealers service centers. Yes, I live in Vegas. Sure would appreciate some advice and help with this issue and maybe even decoding my VIN number. Thanks in advance, Dave.