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With the reserve light on, there are on average 50-80 km left, depending on the model and driving style. It is only an estimate, though: regularly driving on reserve damages the pump and the filter, especially on common-rail diesels.

What it means

The reserve volume declared by the manufacturer (often 5-9 litres) is left in the tank. The trip computer calculates the range from recent consumption, so on the motorway the figure is more optimistic than in town.

Why you should not run dry

• The fuel pump is cooled and lubricated by the fuel itself
• Sediment at the bottom of the tank is drawn in and clogs the filter
• On diesels, priming often requires bleeding the system
• On some cars running dry can damage the catalytic converter due to misfiring

What to do

• Refuel within the first few kilometres of reserve, without chasing records
• If the car has stalled from running dry, do not insist with long cranking
• If it still runs roughly after refuelling, have the filter and fuel pressure checked

How MasterTuning helps

We read the ECU with professional tools, interpret the real fault codes and tell you what really needs repairing, without unnecessary replacements. Diagnosis, repair and software recalibration at our centres throughout Italy.

Read more: vehicle database · find an installer · what is ECU remapping

Is a warning light on? Contact us for a diagnosis or find your nearest MasterTuning centre.

Frequently asked questions

How many km can you drive with the reserve light on?

On average 50-80 km, but it depends on the model, load and driving style: the trip computer figure is an estimate based on recent consumption.

Does running dry damage the engine?

It can damage the fuel pump and dirty the filter; on diesels the system often needs bleeding to restart.

Why does the displayed range drop so fast?

Because it is recalculated from instantaneous consumption: uphill, in town or with the air conditioning on the value falls more quickly.