Blog Car Care Advice 5 Critical Bad Fuel Filter Symptoms + How to Fix It
Car Care Advice

5 Critical Bad Fuel Filter Symptoms + How to Fix It

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Do you feel your engine stalling
Experience a loss of power when stepping on your gas pedal? 

That could be your fuel filter begging for a change.

Your car’s fuel filter is a small component with a big responsibility – guarding your engine against the dark forces of dirt and debris. 
But even heroes can falter. 

Keep reading to uncover bad fuel filter symptoms so you can spot them before they leave you stranded. We’ll also clue you in on the perfect time for a swap and how much that’ll cost you. 

This Article Contains:

What Do Fuel Filters Do? 

Fuel filters protect your engine, fuel injector, fuel pump, and other parts by filtering out impurities found in fuel, such as rust and dirt. 

Most vehicles have two fuel filters — one is located in the main fuel line coming from the fuel tank. Meanwhile, the other filter is non-serviceable and mounted inside the fuel pump assembly in the fuel tank.

The filters feature holes with diameters smaller than a human hair that effortlessly strain the contaminants and purify your fuel before it hits your fuel system. This ensures a clean fuel delivery to the combustion chamber, thereby improving engine performance and longevity.

So, how do you know when your fuel filter goes bad?

5 Potential Bad Fuel Filter Symptoms

From an engine misfire to a lit check engine light, here are some warning signs of a bad fuel filter you should look out for:

1. Loss of Power Under a Heavy Load

Even if your engine runs smoothly when idle, a bad filter can cause trouble when you step on the gas pedal or haul a heavy load.  

A clogging fuel filter means the fuel rail doesn’t get sufficient fuel, and the engine can’t produce enough power. This leads to a noticeable decrease in power when accelerating, going uphill, or carrying a load. 

2. Stalled Engine

If contaminants, like dirt and debris, clog your fuel filter, it can restrict the fuel flow to the engine. This may lead to stalling or total engine failure. 

This can be particularly dangerous if you’re driving in remote or less populated areas, as it can leave you stranded without easy access to help.

3. Rough Idling 

A faulty fuel filter causes low fuel pressure, leading to a lean fuel mixture — too much air and not enough fuel in the engine’s combustion chamber. 

This imbalance disrupts the optimal air-fuel ratio required for efficient combustion. It results in a rough idle or an engine misfire, as the engine struggles to maintain stable operation without sufficient fuel. 

Sometimes, it’s also accompanied by sputters, shaking, hard starting, or an inconsistent RPM rate as you drive the car. 

4. Fuel Inefficiency 

Your fuel filter issues can affect fuel supply and prevent your engine from getting the right amount of clean fuel it needs. 

If you notice a low fuel efficiency or a severe hit to your Miles Per Gallon (MPG), it may be time to check your fuel filter. 

5. Lit Check Engine Light

When a check engine light turns on, look for error codes using an OBD-II scanner. For instance, If the scanner reveals the P0171 error code, it indicates a lean fuel mixture, potentially pointing to a fuel filter issue.

In such cases, you should get a car service ASAP to ensure a clean fuel supply and prevent costly repairs. 

However, you can avoid these and other fuel consumption headaches if you get a new fuel filter in time. 

When Should You Change the Fuel Filter?

You should have your fuel filter replaced every 2 years or 30,000 miles.

However, if you drive on dusty, unpaved roads or through highway construction, you may need to get a new fuel filter more often. 

Tip: Checking and replacing your car fuel filter when you get an oil change is a smart way to stay on top of regular car maintenance. You can also check your car’s owner’s manual for the recommended interval.

Next, let’s find out how to change a dirty fuel filter.

How to Replace a Clogged Fuel Filter

Diagnosing and replacing a bad filter might require additional technical knowledge, so it’s best to take your car to a repair shop instead of attempting a DIY.

Here’s how a seasoned automotive professional will diagnose a dirty fuel filter:

  1. They’ll empty the car fuel filter and locate the fuel filter’s inlet. This is usually marked “in” or by an arrow showing the fuel flow direction. The mechanic will wipe it clean using a shop towel.
  1. They will lay a disposable rag on the workbench and softly blow downwards into the fuel filter’s inlet.
  1. If the fuel filter is clogged, they won’t be able to blow into the inlet easily. But if it isn’t, they’ll be able to blow through the inlet without much resistance.

Here’s how they’ll replace the blocked fuel filter:

  1. They’ll remove the fuel pump fuse from the car’s fuse box (usually located under the bonnet or the cabin). The mechanic will put your car in neutral or park, start, and run the engine for a few minutes to depressurize the fuel line.
  1. Next, they’ll use a socket wrench to detach the negative car battery cable to ensure the car won’t start while you’re working on it.
  1. The mechanic will locate the fuel filter and clean the fuel lines and surrounding areas with a rag.
  1. They’ll loosen the clips, fittings, or bolts holding the filter in place and disconnect the fuel lines. The mechanic will place a container under the filter to catch any run-off fuel.
  1. Then, they’ll take the old filter out and fit in the new filter. 
  1. Finally, the mechanic will reconnect the fuel lines and car battery cable.

Wondering how much this will cost you?
Let’s find out.

How Much Does a Fuel Filter Replacement Cost?

Depending on the type of fuel filter and labor charges at the repair shop, a fuel filter replacement can cost you around $70 to $150.

Remember, driving with a dirty fuel filter can result in a bad fuel pump, fuel injector damage, fuel pressure issues, poor engine performance, and increased fuel emissions. It can also lead to other costly repairs, like replacing a catalytic converter

That’s why you shouldn’t put off this replacement. 

Get Your Fuel Filter Issues Fixed at AutoNation Mobile Service

Staying on top of fuel filter issues is critical in fighting poor fuel economy and subpar engine performance. You should follow your vehicle’s maintenance schedule and get your fuel filter checked out at the first symptom of a bad fuel filter. 

And if you’re feeling too lazy to take your vehicle to a car service center — contact AutoNation Mobile Service and we’ll bring the service shop to you. 
We’re a mobile auto repair and maintenance service available seven days a week. We offer upfront pricing, convenient online booking, and a 12-month, 12,000-mile warranty on all repairs.

Contact us, and we’ll fix your fuel filter and other car troubles in your driveway.