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iStick TC40W: Overview, Tutorial and Instructions

The latest re-iteration of the iStick adds temperature control to the iStick’s impressive list of abilities, allowing you even greater control over the your vaping experience and virtually eliminating the danger of a dry hit.

I’ve struggled to find much I don’t like with this device.

For the compact size it’s extremely powerful, it comes with advanced vaping features and is sleek and attractive – some people have mentioned a very slight rattle when you shake it hard, but I find it barely noticeable.

Despite the inbuilt 2600mah battery, I have found that the battery life is not as good in temperature control as in variable wattage when is using kanthal wires, although theoretically it should be better. 

40w is more than enough for people who are using a variable voltage/wattage device and are looking for the next device to move up to. Vapers who want more power might want to check out the 80 watt iStick Power 2.

IMPORTANT – to make use of the temperature control features of the istick TC40W, you need to use a nickel temperature sensing coil. Temperature sensing coils are available for here, and are compatible with the Aspire Atlantis, the Fury Tank from AnyVape and the Aspire Triton tank.

What we like:

  • advanced but easy to use temperature control (TC)
  • switch between temperature control or variable wattage (VW)
  • easy to use sub-ohm capability
  • the sleek, compact, and attractive design the istick is famous for
  • improved raised, round fire button
  • reasonably priced introduction to temperature controlled vaping

What we don’t like:

  • very slight rattle when you shake the device
  • difficult to see display in bright sunlight
  • could do with more room for pushing buttons
  • battery life when used in temperature control could be better


  • Overview
  • Why Use Temperature Control?
  • Charging and Battery Safety
  • Setting up the Tank
  • How to switch between TC and VW mode
  • How to use TC mode
  • How to lock the resistance of the coil
  • Do you need to lock the coil?
  • How to use stealth mode
  • How to lock/unlock variable wattage mode
  • How to flip the screen
  • Screen Displays
  • Troubleshooting


  • Thread: 510
  • Variable Wattage: 1 – 40w
  • Temperature range: 100-315℃/200-600℉


  • Undervolt Protection
  • Resistance Detection
  • Overheat Protection
  • Short Circuit Protection


  • Temperature Controlled range: 0.05-1ohm
    Variable Wattage range: 0.15-3.5ohm


  • Capacity: 2600mAh
    Rated output wattage: 1-40W

For full specs and features click here.

Why Use Temperature Control Vaping?

As you use your electronic cigarette, the temperature of your atomiser is constantly changing. Temperature controlled mods can maintain a consistent temperature by detecting the resistance change of the atomiser during heating.

For a full overview of temperature controlled vaping see Temperature Controlled Vaping: All You Need to Know.

Do note that NI200 nickel coils are used for TC mode in the iStick 40w, and it is important that you change the tank when you switch from VW mode to TC or vice versa.


  • Avoids dry hits by setting the temperature below the burning point of cotton (approx 420F).
  • Allows a more consistent flavour as the coil is maintained at a constant temperature, as opposed to variable wattage vaping when the coil is constantly changing in temperature.
  • Theoretically allows for a longer battery life and reduced e-liquid when used in tc mode, as illustrated by Eleaf below:

iStick-TC40W_1 iStick-TC40W_02 iStick-TC40W_03 iStick-TC40W_04

However, in practice I find that the TC mode uses more battery life than VW mode, perhaps because the ‘brain’ of the istick is working harder. There is, though, a definite saving on e-liquid consumption!

You will need to spend a bit of time to find that sweet spot when using temperature controlled (but it’s well worth doing so).

Who is it for?

While not for the beginner, this box mod provides a good introduction to temperature controlled vaping.

It’s also ideal if you are already using variable wattage devices, and would like to try temperature controlled vaping – because if TC mode is not for you, you can fall back to VW mode.


Charging the iStick TC 40w.

As with all box mods, give a good initial charge before first use. The Eleaf is charged with a micro-usb charger (charger supplied but you will need a plug adaptor if charging from a wall plug). It will take roughly 3.5 hours to fully charge the iStick using a 1A wall adaptor.

When charging the battery indicator will flash – when full charged this will stop. When the battery level goes below 10% the battery indicator will flash again. (Note that the OED screen will shut off when charging.)

Battery safety: As always, only use with a compatible charger. See our battery safety infographic for full safety guidelines.

Setting up the Tank

You will need to use a tank with a temperature controlled coil. So if using the AnyVape Fury Tank, for example, you would need to change your usual coil to a TC coil.

As usual, ensure you prime your new coil first by dripping some e-liquid onto the coil and also allowing some time for the e-liquid to soak from the tank into the coil.

When your first use your iStick 40, you may get the following message:

New Coil Up Same Down

If it is a new coil in the tank, press up. If it is an existing coil, press down. If you lock the coil, you won’t get this message, but make sure you unlock the coil before changing/replacing it. (See below for more information on locking or unlocking the coil.)

How Do You Switch Between Temperature Control and Variable Wattage?

Hold the centre button between the two arrows to switch between temperature control and variable wattage.

Bear in mind that you will need different coils for the different mods. So while you can use a regular coil for variable wattage vaping, you will need a TC coil for TC vaping. The Aspire TC coils are clearly marked with a red o-ring.

The device will not function properly in TC mode with a kanthal coil, and functions periodically in VW mode with a TC coil. If it does not function because the wrong coil is being used you will get the message:

Atomiser Low

Using a TC coil in VW mode (or vice versa) can also damage the coil, so it’s worth checking to see if it is in the right mode.

How Do You Use The iStick in Temperature Control Mode?

TC mode.

Use the arrows to increase or decrease the temperature. The temperature will go up or down by 10 degrees fahrenheit each time you press the button – hold the button down and the accelerator will kick in.

(In contrast to some other devices, you can only adjust the temperature in temperature controlled mode, not the wattage, with the device automatically adjusting the wattage to produce the temperature required.)

Once you go past 600 degrees fahrenheit, the device will change to celsius, and will increase to a maximum of 315 degrees celsius in 5 degree increments.

Note that if you are using a coil which is more than one ohm, the device will automatically flip out of temperature control mode because the temperature control range is limited to a maximum resistance of 1 ohm. In addition, if the temperature gets too high, temperature protection will kick in and cut off the device.

If you use the iSitck 40 in unlocked mode, then remove and replace the same tank, you will again get the message:

New Coil Up, Same Down

This time, of course, press the down button so that iStick knows you are using the same atomiser (at the same resistance).

How Do You Use The Variable Wattage Function?

Simply press the up and down buttons to adjust the wattage in 0.1 increments. To change the voltage faster simply hold the button down, and the accelerator will kick in to speed up the voltage change.

Additional Functions

How do You Lock the Resistance of the Coil?

The resistance of the coil varies through the day. By locking the coil you lock the baseline resistance.

If you attach a TC coil which is warm from recent use, the resistance will be higher than usual. If it is cold, the resistance will be lower than usual. So TC coil resistance should always be measured at room temperature before locking the coil.

To lock the resistance of the coil, press the fire button and the up button at the same time. If you remove the tank and will replace it you will get a new resistance reading which takes into account the temperature of your coil – simply place the fire button once to get the locked resistance back again.

Important: When changing coils, ensure you unlock the resistance (press fire button and unlock again) in order to get a new reading on the new coil. I’ve also heard from one user who didn’t unlock the coil before changing it and then found his iStick in permanent lock mode.

Do you need to lock the coil?

As we’ve seen, TC compatible devices automatically change the voltage put through to maintain a constant resistance. So why lock the coil?

In fact, you’re not actually locking the coil, you are locking the baseline resistance. This helps the device calculate the change in resistance from the baseline and also means you do not have to select new or existing coil every time you re-attach your tank to your iStick. (CHECK)

How Do You Use Stealth Mode?

The iStick 40 watt also comes with a stealth mode. Unfortunately, this won’t render you invisible or even camouflaged, but it does switch OED display off – incredibly useful if you are involved in night time combat operations 😉

To switch between normal and stealth mode simply hold down the fire button and the down button at the same time.

See How to Stealth Vape Like a Pro! if you really want to stealth vape!

How Do You Lock/Unlock Variable Wattage Settings?

Hold the two arrow buttons together simultaneously to lock or unlock your wattage settings. So if your preferred setting is 30 watts, you can lock your device at this wattage.

How Do You Flip The Screen?

Like the iStick 30 watt, this device comes with a flip screen feature designed to ensure it is suitable for both right-handed and left-handed vapers. To flip the screen first turn the device off and then hold the up and down buttons simultaneously.

Screen Displays

The Eleaf iStick screen display.

Temperature Control Mode

Temperature (F or C): The temperature which the coil will be heated to.
Resistance (Ω): The resistance of the coil needed, displayed in ohms.
Voltage (V): The voltage required to produce the wattage (see voltage, watts and ohms for an explanation).
Coil (Ni): The coil being used in the tank.

Variable Voltage

Resistance (Ω): The resistance of the coil needed, displayed in ohms.
Voltage (V): The voltage required to produce the wattage (see voltage, watts and ohms for an explanation).
Wattage (W: The wattage the device is set to.

Screen Messages

Over 10 Seconds: Displayed when the device cuts out after it has been fired continuously for 10 seconds.
Battery Indicator: Will flash when reaches 10% or less.
New Coil Up, Same Down: Select up for new coil, down for existing coil (see above for more detail).
Atomiser Low: Atomiser Issue (see troubleshooting below).
Temp Protection: Temperature protection has kicked in to stop the atomiser from heating to above the set level.

Compatibility in temperature control mode

The iStick 40 watt is compatible with the following tanks:

The Fury Tank
Triton Tank
The Kanger SubOx Mini

It will also work with any other 510 threaded TC-compatible tank/atomiser with nickel coils. (I haven’t tried it with titanium coils yet – if you have, let me know how you got on with it in the comments!)


Device Cuts Out

It is possible for the battery to cut out because of the overheating protection function. In this case, it is best to leave the device until the battery to cut out.

Atomizer Low

This can be  caused by using a temperature controlled atomiser in wattage mode (or vice versa). This can damage the atomiser. To fix, replace with a regular atomiser before using in wattage mode, and switch back to a TC atomiser to use in TC mode.

It is possible to get an atomiser low message even when using the correct atomiser

Try the following fixes to resolve the issue.

  • Twist the atomiser to ensure there is a firm but not hard connection between the atomiser between the battery.
  • Remove the tank and clean the connections. (If tissue doesn’t work, try alcohol. (On the connections, not drinking. Although both together should work too.))
  • Remove and replace the atomiser. This should allow you to identify if there is an issue with the battery or the tank.

For even more info on the IStick 40W, see this great video from PBusardo:

30 thoughts on “iStick TC40W: Overview, Tutorial and Instructions”

  1. Hi just replaced coil and now I am having difficulty inhaling there seems to be resistance
    I hope someone can help

      1. Is it safe to push the Eleaf Istick up to 600 degrees on TC for vaping? I find that flavor and vapor are nearly nonexistent at the recommended 420. I do use Ni200 coils and adequate juice, but have been reading about Formaldehyde formation at certain temperatures with Vegetable Glycerine and Propelene Glycol.

  2. Worked fine for first tank of e juice now very harsh no matter what. So I changed coil, but still very harsh. Any idea what else I can check

  3. Hi all, got a problem with my iStick TC40w saying no atomizer none of the above seem to be working I’ve tried them all any other suggestions please?

  4. When I press the button to use, the display says “lock” and nothing happens. What it this and how do I fix it please?

      1. I have just purchased this and continue to have ‘no atomizer’. I have unscrewed and placed it back on but nothing seems to work. Can you help?

      1. Hi Angela, always best not to leave email addresses in comments as they can be picked up by spam lists 🙂

        Try leaving your device in the fridge for a couple of hours, as this can help sometimes. Failing that, pliers usually work, but be careful not to damage the coil.

        1. Hi Leila, the coil is part of the tank, which is separate from the iStick. Changing the coil can vary but you can see an example of a coil being changed here: https://www.ecigarettedirect.co.uk/ashtray-blog/2014/01/beginners-guide-clearomisers.html#atomiserwick

          Coil life depends on many factors such as they type of coil, wattage, e-liquid used but generally if the taste starts to go off it’s usually time to change the coil (if not, it’s probably worth changing after two weeks or so).

  5. My istick tc40watt is showing no atomizer. I don’t understand. Do i not have a connection? How do I fix or replace this?

  6. Hi I have an eleaf I stick 40 watt and currently using temp control. I would like to purchase watt coils and have a seance Heracles tank , do you know what coils I need ! Help please

    1. Hi John. Could you tell me what tank you are using? The iStick 40W TC is the battery and can’t be filled. Thanks

  7. Just wanted to say thank you for this guide. It helped me quickly and thoroughly understand the capabilities of the iStick tc40w when I first bought it and needed some info as a newb. I’ve been using my iStick TC40w for about 2 years, and I always come back to this page if I forget a certain spec. Came back today to confirm that it can safely use coils down to 0.15 ohms. Very well put together spec chart/guide/review. Thanks for keeping this available and putting time into making the page, so that newbs like me could understand. Two thumbs up, have a good day.

  8. Can someone tell me what type coil is used for this device and where can I get one? My local vape shops done have them. So confused.

  9. My unit is fully charged but it will not turn on! Only thing the unit seems to respond to is pushing the two arrows to flip the screen then it turns off again!

  10. Please help every time I press the button to vape it says lock on screen I have tried to push 2 arrow buttons at same time with no luck

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