Blog Car Care Advice 5 Prominent Symptoms of a Clogged Fuel Filter (+How to Check)
Car Care Advice

5 Prominent Symptoms of a Clogged Fuel Filter (+How to Check)

Looking for a mechanic near you for maintenance or repair? AutoNation Mobile Service brings the shop to you. Get a free instant quote today.
Get a Quote

Of all the intricate pieces your car needs to function, the fuel filter may be the most underestimated. Responsible for safeguarding your engine from harmful dirt and contaminants, the fuel filter is a small yet mighty part that protects your engine’s performance and longevity.

However, with time, it can become clogged and cause a host of issues that can result in costly repairs. Knowing the signs to look out for can reduce car-related headaches. 

Read on to explore some common symptoms of a clogged fuel filter, how to check it, and more. 

This Article Contains: 

Let’s get started. 

What Does a Fuel Filter Do?

Fuel will always contain some impurities that can damage your engine components. Common contaminants include sulfur, metals, and water, which can lead to engine problems, reduce fuel efficiency, and create harmful emissions. 

Your car’s fuel filter ensures none of this happens by removing dirt and debris from the fuel before it reaches the combustion chamber. This way, it shields engine parts like the fuel injectors from unnecessary damage. Since it receives quite a lot of wear and tear itself, the fuel filter needs replacing fairly frequently.

Let’s look at some telltale signs of a blocked fuel filter.

5 Symptoms of a Bad Fuel Filter

There are many potential indications, but these tend to be the most common bad fuel filter symptoms:

1. Check Engine Light is On 

A bad filter can cause low fuel pressure, reducing the amount of fuel each fuel injector receives. This can be enough to activate the check engine light. You can double-check this with an OBD-II scanner, which should display a ‘P0171’ code.

2. Reduced Fuel Economy

When a clogged filter obstructs the fuel supply, the Powertrain Control Module reads it as a lean air-fuel mixture and compensates by increasing the fuel to boost engine performance. This can reduce fuel efficiency and create additional problems by putting strain on the fuel pump and fuel injector. 

3. Engine Misfire or Rough Idling

The engine will struggle if it receives an insufficient fuel supply. If the fuel filter is too blocked, it can lead to more air in the air-fuel mixture, leading to an engine misfire or rough idling. You may also notice the engine stalling more frequently. 

4. Poor Engine Performance

When accelerating hard or carrying a heavy load, you may notice poor acceleration or poor engine performance in general. Since there’s an insufficient fuel supply in the combustion system, the engine can’t generate the power it needs. Without sufficient fuel, your car might struggle to accelerate past low speeds.

5. Hard Starting

If your fuel filter is blocked enough, it may restrict the fuel supply in the combustion system to the point where your engine struggles to turn over. In cases where the fuel filter has never been changed, the engine may not start at all.

Now that we know the signs and symptoms, let’s see how a mechanic would replace the fuel filter.

How to Replace a Fuel Filter

If you suspect your fuel filter needs replacement, there’s a standard procedure. 

Before diving in, it’s important to point out that you’ll be dealing with exposed fuel once you open the fuel line. If you’re uncomfortable with fuel fumes, booking a car service is your best bet. 

Here’s how a mechanic will replace it: 

  1. Relieve fuel pressure: First, the mechanic will unplug the fuse for the fuel pump.  They’ll then start the vehicle. If the car cranks but the engine doesn’t start or briefly starts before dying, the mechanic has removed the correct fuse. 
  1. Locate the fuel filter: Most fuel filters sit near the back of the car. Others may be in the engine compartment. However, it may be in the fuel pump assembly inside the fuel tank. In this case, the mechanic would need specialized tools to access it.
  1. Disconnect the fuel filter: Most fuel filters have a quick-connect clip, but threaded fittings hold others in place, which can be tricky to remove. The mechanic will need eye protection when disconnecting the fuel filter, as there may still be some fuel in the system.
  1. Bleed the fuel filter: Removing any remaining fuel from the dirty fuel filter before disposing of it is essential. To do this, the mechanic will place a container underneath the vehicle and remove each fuel line on either end of the filter. They’ll let the system drain for 30 seconds or more until there’s no more fuel. 
  1. Install the new filter: Next, the mechanic will put the new filter in and securely fasten it. They’ll install the new filter the same way as the old one, as the fuel flow can only move in one direction through the filter. 
  1. Reinstall the fuse: Once the new filter is in, they’ll reinstall the fuel pump fuse. If everything runs normally and no fuel leaks from the filter, your car will be good to go.

Next, let’s see how long a fuel filter typically lasts. 

How Long Do Fuel Filters Last?

Generally, most fuel filters should last around 2 years or between 20,000 and 150,000 miles. Since that’s quite a wide margin, your best bet is to consult the owner’s manual for a more accurate estimate. Additionally, you should have the fuel filter switched out more frequently if you’re driving an older vehicle. 

Although your fuel filter tends to have a predetermined lifespan, you can do a few things to make it last longer.

How to Prevent a Fuel Filter from Clogging

Here are some proactive steps you could take:

Wondering if you can drive with a faulty fuel filter? 
Let’s find out. 

What Happens if You Drive With a Clogged Fuel Filter

Driving with a bad filter can lead to more serious issues. A bad filter can restrict fuel flow, increasing the strain on the fuel pump and other engine components.

Additionally, because the engine isn’t receiving sufficient fuel, you may notice reduced engine performance, increased emissions, and, rather counterintuitively, increased fuel consumption. If left long enough, a faulty fuel filter can also damage other fuel system components, such as the fuel injectors.

Wrapping Up

There are many potential symptoms of a clogged fuel filter. The engine light should be the first indication, but you may notice reduced fuel economy, engine stalling, and increased emissions. A blocked filter can prevent your car from starting if it goes unchecked.

When you notice any bad fuel filter symptoms, your best bet is to book a car service with a reputed mechanic like AutoNation Mobile Service for a quick fuel filter replacement. Our mobile mechanics can replace your dirty fuel filter directly from your driveway. We’re available seven days a week and offer 12 months | 12,000-mile warranty

Contact us, and we’ll set you up with a  hassle-free fuel filter replacement.