Chief ReliableApp guides us through:

The thermistor is directly related to E1 error code. There are different resistance levels at different temperatures. I would try this thermistor test and more than likely I would replace the thermistor

The machine control electronics monitors the

exhaust temperature using the thermistor, and

cycles the heater relay on and off to maintain

the desired temperature.

Begin with an empty dryer and a clean lint

screen.

1. Plug in dryer or reconnect power.

2. Set the following configuration:

➔ Door – must be firmly closed

➔ Press Control On

➔ Press End Of Cycle Signal (Louder)

➔ Press Start

3. If after 60 seconds, E1 or E2 flashes in the

display and the dryer shuts off, the thermistor

or wire harness is either shorted or open.

➔ Unplug dryer or disconnect power.

➔ Check wire connections at the machine

control electronics and thermistor. See

Accessing & Removing the Electronic

Assemblies, page 7, and figure 8 for

thermistor location.

➔ If wire connections are good, remove the

two wires from the thermistor and replace

the thermistor

And Sublime Master KurtiusInterupptus offers this caveat:

Just because the thermistor checks good @ room temp doesnt. Mean it stays within tolerance as it heats up...

replace it.

Thermistor part link ==> Thermistor

And how to replace it:

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Source: Whirlpool Duet GEW9200LW1, E1 error code