Fuel preheater – with full power through the winter

DIESEL-THERM Fuel heater – with full power through the winter
  • The solution for freezing problems with diesel and biofuels
  • Prevents clogged fuel filters due to fuel gelling in winter
  • Keeps fuel fluid at extremely low temperatures
  • Gentle engine warm-up – less fuel consumption
  • Economical and engine-friendly by eliminating diesel additives
  • Reduces exhaust emissions
  • Easy and quick installation with detailed instructions
  • Suitable for diesel vehicles and diesel engines of all kinds: Cars, SUVs, vans, trucks, buses, tractors, agricultural machinery, construction machinery, generators, etc.
  • Maintenance-free system
  • Proven technology – Made in Germany

The problem …

Diesel freezes at minus temperatures

Diesel and biofuels gel at temperatures below freezing. Paraffin crystals form in the fuel, making it gelly-like and flaky. As these suspended flakes pass through the filter, they gum up its microporous surface. Within a short period of time, the fuel will no longer flow through the filter to the injection system. The result: the engine loses power and stops running.

Adding gasoline or additives to prevent fuel gelling offers no real solution but only seem to help on a limited basis. They can have a negative effect on the engine´s performance and life cycle, not to mention, they must already be added before it turns cold.

Also “Winter diesel” (formulated especially for winter usage) does not guarantee a smooth running engine. Winter diesel is laboratory tested to -20 °C. At lower temperatures and wind chill, it is unclear whether the engine will even run. In any case, the engine works unregularly, resulting in a increase of fuel consumption.

To prevent the fuel filter from waxing, only the supply of warmth can avoid the problem. Heat ensures a smooth engine operation and prevents the increased consumption in winter.

… The solution

The DIESEL-THERM fuel heater is the effective and permanent solution to avoid cold problems with diesel and biofuels.

DIESEL-THERM prevents the filter´s pores from clogging up even at extremely low temperatures by warming the fuel with a small heating system, which is mounted in front of the filter. Within a matter of seconds, the energy-rich paraffin crystals will dissolve and the fuel passes through the filter as if it would be summer.

DIESEL-THERM filter heating

DIESEL-THERM filter heating

By controlled preheating of the fuel temperature-related operating problems will be effectively eliminated from the critical part of the fuel system and fuel additives are not required anymore.


To prevent cold-flow problems or a loss of power due to a waxed fuel filter DIESEL-THERM is activated for the winter operation by a rotary switch. The heating process is displayed by a pilot lamp and automatically regulated by a thermostat.

Installation and scope of delivery

DIESEL-THERM is available as 12 and 24 Volt model in different versions:

DIESEL-THERM screw/filter version DHScrew/filter version DH for filter inlet

The screw/filter version DH is installed instead of the existing banjo screw (thread M14x1.5 / spanner width 19 or thread M16x1.5 / spanner width 22) at the filters entrance. Alternative thread sizes are available on request.

DIESEL-THERM universal version DHSUniversal version DHS for rubber hose

The universal version DHS is installed in the fuel line (flexible rubber hose) with 08, 10 or 13 mm inside diameter (ID) in front of the filters entrance.

DIESEL-THERM universal version DHSEUniversal version DHSE for plastic/metal pipe

The universal version DHSE is installed in the fuel line (inflexible polyamide/metal pipe) with 08, 10 or 12 mm outside diameter (OD) in front of the filters entrance by means of Ermeto compression fittings.

DIESEL-THERM installation kitFollowing components are included in delivery of DIESEL-THERM:

Electric continuous-flow heater (12 V, Pmax 200 W / 24 V, Pmax 300 W), temperature switch (regulates temperature), rotary switch with pilot lamp, relay, cable loom with connectors, fuse and protective caps, miscellaneous materials, detailed installation instructions


The company ATG has been active for more than 30 years in the field of fuel preheating. DIESEL-THERM is for example used by: Caterpillar (CAT), BayWa, Deutz, Faun, Fuchs, Hitachi, Honda, Iveco Magirus, Kaessbohrer, Kramer, Liaz, Liebherr, MAN, Mitsubishi Motors, Nissan, Toyota, Zeppelin.

“We have no more problems with clogged fuel filters. Because of this experience we will offer DIESEL-THERM also in the next winter season.”
BayWa AG
“After careful examination of your diesel heating system we decided to equip our snow groomers with DIESEL-THERM.”
Kaessbohrer Gelaendefahrzeug AG
“Meanwhile we installed DIESEL-THERM in our own vehicle fleet and recognized that your product improves the operation with biodiesel noticeable at extreme coldness. It’s in our interest to offer DIESEL-THERM also to our customers.”
“At temperatures of -25 °C DIESEL-THERM satisfied our requirements. We have no more cold-flow problems in our machinery.”
Anton Vihl construction machinery service
“With DIESEL-THERM our vehicles have always been ready for use, even at very low temperatures and after parking in winter sport locations, without using any flow improvement additives.”
Town Council Kirchweihtal
“Our planning department tested and released DIESEL-THERM based on the last year’s experiences. It impresses by a very good price-proficiency-relation.”
Iveco Magirus AG
“We have no longer problems with fuel gelling at our passenger cars and trucks in the local and long-distance traffic by using DIESEL-THERM.”
ATB Swiss
“With DIESEL-THERM the fuel consumption dropped noticeable and the smoke formation was considerably lower.”
Auto-Klinik Hoffmann

FAQ – Frequently asked questions

Which DIESEL-THERM version fits to my vehicle?
Due to the wide range of vehicles or engines on the market, it is almost impossible to make a type-specific statement. In any case, the type of the fuel pipe (rubber hose, polyamide, metal, …) and its diameter at the entrance of the fuel filter needs to be determined. In case of doubt, please do not hesitate to contact us.
Where can I order DIESEL-THERM?
DIESEL-THERM is available directly from ATG or ATG partners.
Where can I have DIESEL-THERM installed?
The installation ca be performed by any reputable garage/mechanic. Craftmanship and an understanding of diesel engines provided, a DIY (do-it-yourself) installation with the included installation notes is also possible.
Is the electrical preheating of fuel generally allowed?
For your own protection, please check with the appropriate authorities in your country. This has also to be done for any changes on the vehicle.
Is it possible to operate my vehicle with straight vegetable oil (SVO/PPO/WVO) after the installation of DIESEL-THERM?

DIESEL-THERM is used for preheating diesel and biofuels to prevent cold-flow problems through clogged or waxed fuel filters. For heating-up straight vegetable oil to combustion relevant temperatures DIESEL-THERM alone is insufficient. To operate diesel vehicles and motors with straight vegetable oil (SVO/PPO/WVO) our Vegetable Oil Conversion Kits are necessary.