What to Do if You Put Gasoline in Your Diesel Vehicle

If you own a diesel vehicle, you have likely been proactive in locating the diesel pumps in your area and looking for the green-colored pump handles when you arrive. However, we all get distracted at times; something can throw us off our game, and in this case, you may have discovered that you accidentally filled your diesel vehicle’s tank with gasoline. If you’re wondering what happens if you put gas in a diesel engine, acting quickly can help reduce the risk of serious damage.

We would like to say that it’s no big deal, but that wouldn’t be true. Gasoline and diesel have very different combustion properties. Gasoline is thinner and less oily than diesel; however, most importantly, it has a lower energy density yet is more volatile, igniting at lower temperatures than diesel. An engine designed for one and accidentally fueled by the other faces several unfortunate consequences.  

What Happens If You Put Gas in a Diesel Engine?

Accidentally putting gasoline in a diesel engine can cause serious damage if it isn’t addressed quickly. Because diesel engines rely on diesel fuel for both combustion and lubrication, gasoline can reduce lubrication, disrupt combustion, and damage critical components such as the fuel pump and injectors. If you’ve accidentally put gas in your diesel vehicle, the most important step is to avoid driving it and have the fuel system inspected as soon as possible. Below, we’ll explain the symptoms to watch for, the potential damage, and what you should do next.

Common Symptoms of Gasoline in a Diesel Engine

You will first notice a significant reduction in engine performance due to incomplete combustion. This can also result in black or blue smoke from excess unburned fuel, causing the engine to run roughly with occasional stalling. You might also hear a knocking sound similar to that of gas engines running on fuel with too low of an octane. Your first start after using the wrong fuel is likely to be normal because the fuel has not yet reached the engine; however, subsequent starts may be difficult and require repeated attempts. If you experience these issues but know you didn’t mis-fuel, it still could be a gasoline issue. Mistakes have been known to happen in the fuel supply chain.  

Potential Damage to a Diesel Engine After Misfueling

Unfortunately, your issue is not confined to a poorly functioning engine until you properly refill it with diesel. Long-term damage to the engine can manifest in the following ways: 

• Filters and fuel lines: Gasoline will obstruct fuel filters and lines because varnish-like deposits form, hindering the proper flow of fuel. 

• Fuel injectors: The chemical properties of gasoline can harm fuel injectors, clogging the apertures and disrupting their accuracy and capacity to deliver fuel correctly. 

• Pistons and Cylinder Walls: Each combustion will be incomplete, possibly creating hot spots, resulting in overheating and possibly damaging the cylinder walls and pistons. 

• Valves and Valve Seats: Gas contamination can cause valve sticking or damage to valve seats due to carbon buildup, which affects engine compression. 

If You Haven’t Started the Engine 

If you notice the mistake before starting the engine, don’t panic; in fact, congratulate yourself for preventing further trouble. Do not start the engine even just to get away from the pump. Inform the station of your mistake and ask for assistance in pushing your vehicle away from the pump area. If the station has a service facility, you may be in luck if it services diesel engines. Otherwise, you will have to have your vehicle towed to a location where they can:  

• Drain the fuel tank 

• Check to see if the gas has reached anywhere past the tank. 

What to Do If You Already Started the Engine

OK, now things get more involved. Even if you haven’t experienced any of the performance issues discussed above, get off the road and shut off your engine immediately. As above, have your vehicle towed to a facility that services diesel engines. Once there, they will need to: 

• Drain the fuel tank 

• Flush the fuel system including: 

• Fuel pump 

• Fuel filter 

• Injectors 

• Check for any damage to the above and repair and replace accordingly 

None of the subsequent actions are good for your wallet, but acting quickly is always better than delaying or hoping to ride out the issue with a subsequent refueling. If you have further questions, the Service Department at Alderman Automotive is here to help. Although we hope this post brings some clarity to the issue, we hope this never happens in the first place. 

Can a Diesel Engine Be Repaired After Gasoline Contamination?

In many cases, a diesel engine can be repaired if the problem is caught early. If the engine hasn’t been started, draining the fuel tank may be enough to prevent damage. However, if gasoline has circulated through the fuel system, additional repairs such as cleaning the fuel lines, replacing the fuel filter, or inspecting the injectors and fuel pump may be necessary. Acting quickly greatly improves the chances of avoiding major engine repairs.

What to Remember If You Put Gas in a Diesel Vehicle

Accidentally putting gasoline in a diesel vehicle can happen to anyone, but taking immediate action can help prevent extensive engine damage and expensive repairs. If you discover the mistake before starting the engine, avoid turning the ignition on and have the fuel tank drained. If the engine has already been started, stop driving as soon as it is safe and have the vehicle towed to a qualified service facility for inspection.

If you need assistance or have questions about your vehicle, the team at Alderman Automotive is here to help with professional service and expert advice to get you back on the road safely.

Frequently Asked Questions

What happens if you put gas in a diesel engine?

Putting gasoline in a diesel engine can cause rough running, difficulty starting, reduced engine performance, excessive exhaust smoke, and damage to the fuel system. The sooner the contaminated fuel is removed, the lower the risk of costly repairs.

Can one tank of gasoline damage a diesel engine?

Yes. Even a single tank of gasoline can damage a diesel engine because gasoline does not provide the lubrication required by diesel fuel system components. Driving the vehicle increases the likelihood of damage.

Should I start my diesel vehicle if I accidentally put gas in it?

No. If you realize you’ve filled your diesel vehicle with gasoline, do not start the engine. Have the vehicle moved safely and arrange for the fuel tank to be drained before operating it.

How do I know if I put gas in my diesel truck?

Common signs include rough engine operation, reduced power, difficulty starting, knocking noises, excessive smoke from the exhaust, and engine stalling shortly after refueling.

Can a mechanic fix a diesel engine after gasoline contamination?

Yes. A qualified technician can drain the fuel tank, flush the fuel system, inspect the injectors and fuel pump, replace damaged components if necessary, and restore the vehicle to proper operating condition.