11 August 2015

Pay attention to your diesel exhaust fluid levels

Company car and van drivers could find themselves grinding to a halt if they don't react to a dashboard warning light reminding them of the urgent need to fill up with diesel exhaust fluid.

What is Selective Catalytic Reduction?

Low emission diesel models coming to market are now equipped with Selective Catalytic Reduction (SCR) technology.

SCR technology requires diesel exhaust fluid (often known by the German brand name AdBlue®) to be continuously sprayed into the exhaust gas, upstream of the catalytic converter, to assist in the breakdown of harmful nitrogen oxides (NOx).

Most motor manufacturers are fitting diesel vehicles with SCR technology to meet Euro 6 emission standards. These regulations focus on the reduction of NOx, a pollutant that is more prevalent in diesel engines than petrol models.

Mazda is one of the few manufacturers not using SCR to meet tough Euro6 emission levels due to its SKYACTIV diesel engine technology negating the need to use special exhaust fluid.

New Euro6 emissions regulations mean you have to clean up your act

The mandatory timetable for the introduction of Euro6 legislation means that from September 1, it will apply to all newly registered cars and light commercial vehicles under 1,305kgs (unladen weight) and to all new type approvals on light commercial vehicles from 1,305 to 3,500 kgs (unladen weight). From September 1, 2016 it applies to the first registration of existing, previously type-approved vans in the 1,305 to 3,500kgs (unladen weight) category. The Euro 6 legislation has been applicable to all new type approvals on cars and light commercial vehicles under 1,305kgs (unladen weight) since September 1 last year.

Look out for the AdBlue® tank

If a car is equipped with SCR technology it will have an AdBlue® tank. The location of the tank varies across manufacturers and from model to model but is often close to the diesel tank or in the boot, under the carpet, or in the engine compartment. It can usually be identified by its blue cover.

Keep a watchful eye on your fleet – AdBlue® consumption is variable

Manufacturers will typically refill the tank during servicing but consumption of AdBlue® can vary enormously according to vehicle type and model, vehicle load, environmental conditions, driving requirements (for instance, mountain roads or while towing) and driving style – just like with fuel.

Additionally, with many of today’s diesel vehicles having variable servicing intervals, a watchful eye must be kept on tank levels, as the vehicle will not start if the fluid has run out.

To further complicate matters, motor manufacturers calculate that a tank of AdBlue® can last for different amounts of time depending on how economically a car is driven in a similar manner to fuel. Furthermore, AdBlue® tank capacities vary from model to model.

What do the manufacturers say?

  • Peugeot suggests that the AdBlue® tank it uses needs to be topped up approximately every 12,500 miles.
  • BMW says a complete refill will be required after approximately 9,300 miles.
  • Mercedes-Benz highlights that a litre will be sufficient for about 625 miles of driving.
  • Volkswagen suggests its vehicles use the fluid at an average of 0.1 litres per 62 miles (100 kilometres).

Manufacturers additionally suggest that in some cases, drivers will not even notice AdBlue® due to consumption being so low that the vehicle will only need a refill at every service.

Dashboard warning light informs drivers

To help drivers monitor AdBlue® consumption, vehicles are equipped with a special dashboard warning light but once again, the message displayed varies across manufacturers. However, all manufacturers are in agreement that if the tank is allowed to run dry then the vehicle will not start.

BMW models, for example, will give an initial warning with 1,200 miles remaining that AdBlue® is required. Once the fluid range reaches 500 miles, there will be a red warning with a mileage range countdown.

Vauxhall advises drivers to fill the tank with five litres of AdBlue® at the first warning with enough fluid left for 1,500 miles. There are further warnings below 1,050 miles and a message is displayed at every ignition. Once below 560 miles, a continuously flashing message is displayed at every ignition and speed is limited to 60mph and finally when the level becomes too low, a continuously flashing message is displayed at every ignition and speed is limited to 30mph.

Peugeot models display a message informing drivers how many more miles they can drive before the vehicle will not restart. For example, ‘Top Up Emissions Additive: Starting prevented in 900 miles’. When driving, the message will be displayed every 150 miles until the AdBlue® has been topped up.

Where can I find AdBlue®?

AdBlue® can be purchased at retail outlets, dealerships and many service stations throughout the UK.

Before using a service station pump, check if the car can be filled up at it. Diesel exhaust fluid debuted in HGVs and they need to be refilled far more frequently than cars, sometimes every week. As a result, oil companies have developed a network of service stations with pumps that meet HGV requirements including larger nozzles and fast delivery. These pumps are incompatible with cars.