Brand New Prusa I2 not extruding

So i have successfully assembled the Prusa i2 that has a 0.5 nozzle along with other standard gear that comes with the kit. the only issue i have is that the hotend does not get hot enough to extrude 1.75 pla. The recommended temperature of 185 (degrees Celsius) is still relatively warm to touch with my finger and then setting it to abs temp 230(degrees Celsius) slowly melts the PLA when i manually touch the tip. i am using the latest Sprinter Firmware on the device and the only time i got a successfully extrusion is when i set the temp to 160(degrees Celsius). im beginning to suspect a faulty temp sensor. has anyone experienced this and if so what are the troubleshooting steps.

PS: nozzle is clean and unblocked

You say you can touch the nozzle with your finger at 185C? If so, your temp is obviously not 185 - more like 50C!
Also setting the temp lower than spec and having it extrude doesn't make sense either.

Have you got the correct thermistor set in Sprinter?
Have you checked the thermistor resistance when its cold?
Does the resistance drop when you warm it?

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Waitaki 3D Printer