ESP8266 Community Forum

pinMode(16, INPUT_PULLUP)

This does not work for pin 16. It is an exception. It does not have a pull up option, it has a pull down.

pinMode(16, INPUT) and use an external pull up resistor.

GPIO16 can be INPUT, OUTPUT, or INPUT_PULLDOWN_16

Please also have a read in our Wiki (see at the top of the screen), for information about the ESP's GPIO's.