Running on Fumes Isn’t Harmless
We’ve all done it; that little orange fuel light pops up, and you think, “I’ll fill up tomorrow.” The problem is, driving on empty isn’t just risky for getting stranded. It can quietly damage parts of your car that aren’t cheap to fix. Modern engines rely on a clean, steady fuel supply, and when you run low, that system starts to struggle.
So yes, the light might buy you a few miles; but it’s not doing your car any favours.
1. Dirt and Sediment in the Tank
Over time, tiny bits of rust, dust, and debris settle at the bottom of your fuel tank. When you’re running low, the fuel pump starts sucking up whatever’s left; including that gritty layer. The result? Blocked fuel filters and clogged injectors that make your engine run rough or stall altogether.
Replacing filters isn’t too bad. Replacing injectors? That’s a bill you’ll definitely feel.
2. Fuel Pump Damage
In most cars, the fuel pump sits inside the tank and relies on petrol or diesel to keep it cool and lubricated. When you drive with barely any fuel, the pump runs hotter and works harder, shortening its life. Once it burns out, the engine won’t start at all; and replacement can cost hundreds.
Diesel pumps are especially sensitive, as the fuel also lubricates critical components. A few dry runs can do lasting harm.
3. Air in the System
When the tank runs dry, air enters the fuel lines. Petrol engines can cough and splutter until the air clears, but diesels are fussier; they often need the system manually “bled” to remove air bubbles before they’ll start again. That’s one problem you don’t want on a cold morning in the middle of nowhere.
4. Reduced Engine Efficiency
Engines run best with a consistent flow of fuel. When you’re low, the pump has to work harder to deliver pressure, and that can affect performance. You might notice sluggish acceleration, rough idling, or even misfiring if the fuel feed becomes uneven. It’s not catastrophic straight away, but repeated “light-on” driving adds up.
5. Condensation and Corrosion
When there’s lots of empty space in your tank, moisture from the air can condense on the inside walls. That water then drips into the fuel, where it can cause rust and bacterial growth; especially in diesel cars. Over time, it corrodes metal parts and leads to fuel contamination that affects filters and injectors.
Keeping your tank at least a quarter full helps prevent that damp environment from forming in the first place.
6. You Might Run Out When It Hurts Most
Fuel gauges aren’t exact. On steep hills or uneven roads, the reading can change suddenly; so that “ten miles left” might actually be three. Running dry can leave you stranded somewhere inconvenient, or even dangerous, like a motorway hard shoulder. And if that happens in heavy traffic, you could face a fine for causing an obstruction.
7. Hybrid and Electric Vehicles Aren’t Immune
Even hybrids can suffer if their petrol engine runs dry. The car’s systems rely on both power sources working properly, and forcing the fuel side to run empty can trigger error codes and limp mode. For plug-in hybrids, it can even stop the engine from restarting once you refuel; meaning a trip to the dealer just to reset it.
When to Refuel
Ideally, fill up when you reach a quarter of a tank. It’s a simple rule that keeps your pump submerged, prevents sediment from circulating, and saves you from the stress of watching the range counter drop to single digits. It also gives you a buffer in case you hit traffic, get lost, or find your usual petrol station closed.
Useful UK Resources
Running on fumes might save a stop today, but it could cost you a fuel pump tomorrow. Keep that needle above a quarter, and your car will thank you with smoother starts and fewer repair bills. Know someone who’s always pushing their luck at the petrol light? Share this page; it might spare them a breakdown.