Service on your Prins DLM system

Thank you for choosing the advanced Prins DLM (Direct LuiquiMax) LPG System for your car. This DLM LPG system complies with strict European standards covering safety and the environment.

It is important that you read and understand this manual before driving on LPG.

This digital manual gives you general information about Autogas (LPG), and explains the Prins DLM LPG system. Scroll down further for information about the fuel selector switch, refuelling LPG, fuel consumption, safety aspects, maintenance, troubleshooting, general directives and the warranty terms.


Family in car - Prins LPG

General information for driving on LPG (Autogas)

1. The Prins Direct LiquiMax system directly starts on LPG. When the LPG fuel tank is almost empty, the system automatically switches over to petrol. After you filled up the LPG tank for minimum 40% the system will automatically switch back to LPG mode.

2. For a guaranteed life span of the LPG Direct LiquiMax system and optimal driveability it is necessary to follow the prescribed maintenance/checks. We advise a maintenance check for the VSI system at an authorised Prins installer every 25.000 km or every two years. Find the items for maintenance check below. 

3. When you smell gas in or around your car, immediately switch over to petrol and have your car checked at the nearest Prins authorized dealer or Prins service point.

4. After the installation of your Prins system, you will receive a warranty certificate from your installer. This warranty certificate contains all information about your car and your Prins system including warranty terms.

5. It generally is allowed for LPG vehicles to drive and park in an underground parking garage. In some garages there are restrictions imposed by the owner. The owner of the garage may do that by placing signs at the entrance. These signs have to be respected.

6. To prevent the petrol getting over aged it is necessary to drive occasionally on petrol. Prins advices to “almost” empty the petrol tank at least twice a year and refill the tank for at least 25%. If the petrol level is too low the petrol is ageing faster and there is a bigger risk that the petrol fuel pump is running dry and fails.


Autogas or LPG (Liquefied Petroleum Gas) is in most countries a combination of propane gas and butane gas. LPG is produced during the extracting and refining of oil (petroleum) and natural gas. In its natural state it is gaseous but it is stored, under pressure, as a liquid in the LPG tank. LPG is a cleaner fuel than for example petrol or diesel. The use of LPG helps to improve air quality. It is an odourless gas, but to make it easier to identify for example a leak, an odour has been added to it.

The Prins DLM LPG system

The Prins Direct LiquiMax system is developed for motor engines with direct injection of petrol. Direct injection means that the fuel will be injected under high pressure directly in the cylinder instead of before the inlet valves. This LPG system makes use of the original high pressure fuel pump and injectors that inject the fluid LPG under high pressure into the cylinder.

Direct Injection makes a more precise injection of the fuel possible and therefore a higher engine efficiency and up to 15% lower CO2 emissions and up to 98% less particles. The Prins injection system is equal to the original petrol high pressure technology and makes optimum use of the electronics that are already present in the car. With Prins Direct LiquiMax you will not experience a difference in driving on LPG compared to driving on petrol.


1. LPG tank

1. LPG tank with fuel module
The LPG tank takes most often the place of the spare wheel, in the boot or under the vehicle. The Liquid LPG is stored under pressure in the storage tank. The tank is equipped with various safety appendages and an electric pump, together also known as the Fuel module. The pump ensures that the liquid gas circulates and is transported to the high pressure pump on the engine. Unused fuel will be transported back to the tank again.

2. Tank lock off valve
The LPG lock off valve is mounted on top of the tank. It is an electric safety device controlled by the fuel controller (AFC). It shuts off the LPG flow making a switch to petrol in case of system error.

3. Filler
The filling point is mounted on the outside of the car or beside the petrol fuel-filling under the fuel filler flap and is provided with a removable protective cover. This cover must be removed prior to refuelling. A non-return valve in the filler prevents the LPG from flowing back after refuelling.

2. AFC (Alternative Fuel Controller / Computer)

The Prins AFC is located in the engine compartment. This AFC is the electrical control unit for the Prins Direct LiquiMax LPG system. The main functions of the AFC are:
• Safety control
• Diagnostic status
• Fuel delivery control
• Air-fuel-mixture formation

3. Fuel selector switch

The fuel switch is located on the dashboard or on the centre console. With the switch you operate the Prins Direct LiquiMax system. The fuel switch can be used for switching between both fuels, as well as monitoring system status, LPG tank level and diagnostic status.

4. Fuel Management Unit (FMU)

The FMU is located in the engine compartment and ensures that while driving on LPG a fuel return to the LPG tank is possible. Beside that it makes it possible to switch between gas and petrol. The FMU contains a replacement filter that needs to be replaced when system service is required.

5. De hogedrukpomp (brandstofpomp)

Fuse box and relay
The fuses are located in an available place in the engine compartment. The fuses protect the electronic circuit from overloading. The fuse box contains 3 fuses and 2 relays.

6. Boost pump

The boost pump is placed in line with the petrol fuel line. The boost pump increases the petrol pressure during the switch over from LPG to petrol in order to make the switch possible.

Information per subject


When LPG is selected the engine starts directly on LPG. If petrol is selected the engine will start on petrol. The engine will start on the last selected fuel.

Switching from petrol to LPG and reverse
While driving it is possible to switch between both fuels by pressing the fuel selector switch. When the fuel status LED (Prins logo) is illuminated the LPG mode is selected and when the fuel status LED (Prins logo) is off the petrol mode is selected.

LPG fuel level indication
An indication of the fuel level is shown by five tank indication LEDs, each representing approx. 20% of the 80% nett fuel level. If the red LED is illuminated (low level), the last litres of LPG are being used. This means that the tank is not yet completely empty and that there are still some litres of LPG remaining, depending on the size and shape of the LPG tank placed in your car. Due to the system characteristics of liquid LPG injection it is not possible to use the complete capacity of the LPG tank. Some litres will remain in the tank.

The Direct LiquiMax LPG system will keep flushing LPG even after turning off the ignition. The LPG pump inside the LPG tank will be operating during flush operation. Therefore the fuel pump and lock-off valve can be audible during three hours after stalling the car.

Prins fuel selector switch

The fuel selector switch has two selection modes:
1. Fuel status LED (Prins logo) does not illuminate: Petrol mode (driving on petrol).
2. Fuel status LED (Prins logo) illuminates: LPG mode (driving on LPG).
The light intensity of the LPG fuel level indication LEDs varies, depending on the amount of daylight.

If the engine will not start it is possible to use the emergency start procedure. Run the emergency start procedure by turning on the ignition without starting the engine and press the fuel switch button of the LPG system for at least 5 seconds. If you release the button you will hear a continue beep. Now the system will start forced on petrol.

Switching from petrol to LPG and reverse

While driving, you can always switch between both fuels by pressing the fuel selector switch. After pressing the fuel selector switch the switch over prodedure will be started.

Petrol>>LPG: The Fuel status LED flashes. When the system has finished the switch over prodedure the Fuel status LED will be illuminated constantly.
LPG>>Petrol: The Fuel status LED will be extinguished when the system has switched over to petrol.

LPG fuel level indication
An indication of the fuel level is shown by five LEDs. Depending on the tank sensor used the fuel level indication will be displayed in 5 or
6 stages. If the red LED is illuminated (low level), the last litres of LPG are being used. This means that the tank is not yet completely empty and that there are still some litres of LPG remaining, depending on the size and shape of the LPG tank placed in your car. Because of the measuring principle of the system measuring the fuel level, this measurement cannot be any more accurate. It is only an indication of the fuel tank contents. Experience will show how much further you can drive if the red LED is illuminated.


A diagnostic / system check LED and buzzer are integrated into the switch for diagnostic purposes. The following error messages may occur:

1 Tank Empty
Fuel status LED flashes 1x per second and beeper beeps 3 times (Low level LED is on)
Diagnosis: Tank is empty, system switches automatically back to petrol.
Action: Fill up the tank (minimum of 40%), the system will switch back to LPG mode automatically.

2 Critical fault
Diagnose / system check LED is on (red) and the beeper beeps 1 times per second, Fuel status LED flashes 1x per second
Diagnosis: An error has occurred in the Direct LiquiMax system. System switches automatically back to petrol.
Action: Consult your Prins dealer.

3 Non critical fault
Diagnose / system check LED flashes 1x per second (red)
Diagnosis: An error has occurred in the Direct LiquiMax system. Driving on LPG is still possible.
Action: Consult your Prins dealer.

4 System limit reached
Diagnose / system check LED is on (orange) and the beeper beeps 2 times, Fuel status LED flashes 1x per second
Diagnosis: The system temperature has reached its maximum level. LPG operation is not possible. System switches
automatically back to petrol.
Action: During this drive cycle the system will remain on petrol, the next drive cycles the system will reassess the systems’ heat balance on LPG.

5 Service interval warning
Diagnose / system check LED flashes 1x per second (yellow)
Diagnosis: The Direct LiquiMax- system needs a regular service/check-up. Driving on LPG is still possible.
Action: Consult your Prins dealer.

6. Boost pump failure
Diagnose / system check LED is on (red) and the beeper beeps. Fuel status LED flashes 1x per second, tank content indication LED flashes every 2 seconds
Diagnosis: The boost pump malfunctions, switch over to petrol is not possible anymore!
Action: Do not drive your LPG tank empty. Refuel LPG if necessary and drive to your Prins dealer.


Filling the LPG tank:

Step 1: Turn off the engine!
Step 2: Remove filler cap from filler opening.
Step 3: There are four different types of fillers:
Bayonet filler: place fuel pistol in filler opening and turn it a quarter to the right or left. Pull the fuel pistol handle.
Euro filler: tighten fuel pistol nut on filler opening. Press handle on fuel pistol.
Italian filler: place fuel pistol in filler opening. Press handle on fuel pistol.
Euro Nozzle filler: place fuel pistol in filler opening. Press handle on fuel pistol.

Step 4: Press LPG pump button. When the pump stops after a while, the maximum tank level of 80% is reached. Stop refuelling by releasing the button.
Step 5: Now loosen the handle (some LPG may be released) and remove the fuel pistol.
Step 6: Put the filler cap in place to avoid dirt, water, sand and dust from entering the filler opening and therefore the entire system.

Attention: smoking and open flame are prohibited while filling the LPG tank. Also your cell phone must be shut off.

We strongly recommend adding one bottle of Prins InjectorCare (200ml) to every 30 liters (8 gallons) of petrol, preferably prior to each refill of the petrol tank (approx. every 10.000km/6.200mi).
The instruction manual can be downloaded here.

Bajonet filler ACME (Euro) filler Dish (Italië) filler Euro Nozzle filler
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LPG has a lower energy value per volume unit than petrol. Therefore the consumption when using LPG will be approximately 15-25% (depends on the ratio of propane to butane of the LPG you have refueled with) higher than the consumption you are used to get with petrol.

LPG systems for Direct Injection engines
If your car is equipped with a DLM system you have to bear in mind there will always be a little petrol consumption during driving on LPG.


Disassembly of parts/system
Do not attempt under any circumstances to disconnect or disassemble LPG system components. The system is pressurized and contains liquid gas. You run the risk of serious burns when doing this. Only have an approved Prins dealer remove or repair the system.

Gas leakage
If you can smell LPG, switch back to petrol and contact an approved Prins dealer immediately.

In the case of a fire, leave the vehicle and take distance. The LPG tank is equipped with a safety valve that allows the LPG to escape from the tank in case of abnormal pressures inside this tank. Thanks to this device it is impossible for the LPG tank to explode. Always inform the emergency services that you have a LPG system in the vehicle.


When you drive on LPG, maintaining your car is even more important than when using petrol. Since the specifications of LPG differ from those of petrol, minor engine problems which won’t disturb the driving comfort while using petrol, may cause major problems while using LPG.

Follow the maintenance instructions in order to use LPG without any problem.

• General maintenance to the car regarding spark plugs, spark plug cables, ignition circuit, valves, etc., has to be carried out according to the instructions of the car manufacturer.
• Proof of maintenance according to the guidelines of the importer is obligatory (completely filled in maintenance booklet).
• Maintenance has to be carried out by a dealer authorised by the importer.
• Adjustments and repairs on your Prins LPG system should only be carried out by a dealer authorised by Prins.

We advise a maintenance check for the VSI system at an authorised Prins installer every 25.000 km or every two years. These are the items included in the maintenance check:


If your car won’t run on LPG, follow the next checklist:
• Is there enough LPG in the tank?
• Is there enough petrol in the tank for starting on petrol?
• Is a fuse in the LPG system defective (near LPG computer)?

Never use a heavier fuse than indicated on the fuse wire. This may cause damage to the system.
If you cannot solve the problem yourself, please contact your Prins dealer. Do not carry out any repairs or readjustments yourself, but have this done by an authorised Prins DealerOtherwise, the warranty on your Prins system will no longer be valid.


General directive for damage repairs in spray/dry booths
In case of damage repairs to a car with an LPG system, the LPG tank must be removed when the car is placed in a spray/dry booth with a drying temperature higher than 60°C. Otherwise, the opening pressure of the overpressure safety valve will be exceeded.

General directive for dismantling LPG system
When a vehicle with an LPG system is dismantled, be careful with the LPG tank, including pipes, due to possible remaining pressure in these parts. Also remove LPG tank before the vehicle is crushed.

General directive for extreme temperatures
Extreme temperatures and the fuel composition can influence the operation of the LPG system. It may take longer for the system to switch from petrol to gas. In extreme situations the system may switch back to petrol, because the minimum conditions for the proper system operation are not met.

LPG fuel quality
The LPG must be as specified in the DIN EN 589 regulation at a minimum. If a fuel quality other than specified is used, all terms of guarantee become void.


Extract from the General Conditions of Prins Autogassystemen B.V. These General Conditions were deposited with the Eindhoven Chamber of Commerce and Industry on 3 January 2011 under No. 17058344. The complete text of the General Conditions is available on the Prins website.

14.1 Prins warrants that the Products it supplies are manufactured from sound materials and are of sound workmanship. Should defects nonetheless occur in the Products supplied by Prins as a result of manufacturing defects and/or defects in the material, Prins will, after examining the defects in
accordance with Article 14.3, repair the said defects, or cause them to be repaired, within the specified term, or provide the components required for repair, or cause them to be provided, replace the Products in full or in part, or reimburse at most the invoice value of the Products, all this at its sole discretion. This warranty shall apply during twenty four (24) months following delivery.

14.2 Should the Product supplied comprise a complete LPG system, this must have been built in by Prins or by a dealer approved by Prins in accordance with the standard instructions and the statutory requirements; if the system will be registered online (warranty portal) within thirty (30) days of delivery, the warranty period referred to in Article 14.1 shall be thirty six (36) months, subject to written deviations. If no online registration (warranty portal) will be examined, the guaranty term of twenty four twenty four (24) months will start on the delivery date.

14.3 At the request of Prins, the Purchaser shall allow an expert appointed by Prins to examine the defective Product, failing which the right to warranty shall lapse. The decision of the expert shall be binding for both parties. The costs of such expert appraisal shall be borne by Prins if the Purchaser has made a claim under the warranty; they shall otherwise be at the expense of the Purchaser.

14.4 Any claims under this warranty shall be reported to Prins by registered letter within eight (8) days of their occurring. Should the complaint not be submitted within that period, any claim vis-à-vis Prins shall lapse. Any legal proceedings instituted in respect thereof shall be brought before the court within thirteen (13) months of the submission of the timely complaint on pain of their lapsing.

14.5 Should the Purchaser request Prins to repair the Products at the Purchaser’s premises, Prins shall be authorised to invoice the Purchaser for the costs incurred, including travel expenses, accommodation and meals.

14.6 Defects resulting in whole or in part from the following shall not in any case be covered by the warranty:
(a) failure to comply with the directions for use, operating instructions etc. or use other than the intended normal use;
(b) normal wear and tear;
(c) alterations to the information on the warranty card;
(d) alterations to information on the stickers provided by Prins in accordance with its legal requirements;
(e) assembly/installation, repairs or adjustment by third parties, or in any case by a dealer or purchaser not recognised by Prins without Prins’s prior written consent;
(f ) the application of any government regulation on the nature or quality of materials used;
(g) materials provided by the Purchaser to Prins to process or execute an order, unless explicitly otherwise agreed;
(h) materials and/or goods used in consultation with the Purchaser;
(i) advice given by Prins, unless explicitly agreed otherwise;
(j) the processing of Products by the Purchaser, unless Prins explicitly states a specific manner of processing in writing in its documentation brochures etc. or has permitted such without any reservation in writing;
(k) external influences, installation mistakes;
(l) incorrect fuel or fuel of inferior quality;
(m) the use of an additive not approved in writing by Prins;
(n) demonstrable failure to comply with the maintenance schedule prescribed by the car manufacturer, importer and/or Prins.

14.7 Prins shall not be held to any warranty nor shall it be liable to pay any compensation whatsoever with regard to the Contract should the Purchaser fail to comply with any obligation arising for it from the Contract concluded with Prins or from a related contract, or fail to do so properly or on time.

14.8 Any claim under this Article shall expire should the Purchaser carry out repairs, disassembly or other actions affecting the Products, or should it cause such repairs, disassembly or other actions to be carried out, without Prins’s prior written consent.

14.9 Should Prins replace any components or Products in fulfilment of a warranty obligation, such Products or components shall become its property. Prins shall be authorised to charge transport costs for these Products or components unless Prins has given instructions for the transport.

14.10 Without prejudice to the provisions of Article 15, Prins shall in no case be bound by any other obligation, for example to pay compensation.

15.1 Prins shall not be liable for any costs, damage or the like that may arise as a direct or indirect result of:
(a) force majeure, as set forth in these conditions;
(b) acts or omissions by the Purchaser, its employees, or other persons who have been put to work by the Purchaser or on its behalf;
(c) the applicability of one of the circumstances specified in Article 14.6.
15.2 Prins shall only be liable to the extent of its insurance cover for any damage (or personal damage) to Products or property belonging to the Purchaser and/or third parties if such has occurred through any intentional act or omission or gross negligence on the part of Prins or of those who have been put to work by Prins, with the amount insured by Prins being the maximum. Should it turn out, for whatever reason, that no insurance cover exists with respect to a given case, Prins’s liability shall be limited to the invoice value, exclusive of VAT.

15.3 Prins shall in no case be liable for any collateral damage suffered by the Purchaser or a third party, including consequential damage, immaterial damage, loss of profits or environmental damage.

15.4 The Purchaser indemnifies Prins against all claims by third parties in respect of deliveries of Products.