What Does the Fuel Filter Warning Light Mean?

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Diesel engines are quite different from their gasoline counterparts. Besides not using spark plugs, just about every diesel engine uses fuel to lubricate high-precision engine components. Unfortunately, trace amounts of water can be found in diesel fuel and it needs to be removed before it gets to the engine.

Water doesn’t work very well as a lubricant and it could cause excessive wear on the engine if it made its way through the fuel system. To prevent this, diesel fuel filters are designed to separate the fuel and water before it heads to the engine. The water is collected and must be emptied out occasionally, otherwise it will start to pull through the filter and make its way to the engine.

Some vehicles may empty the water automatically or you may have to empty it manually. A warning indicator on the dash will let you know when too much water has been collected and the fuel filter needs to be emptied.

What the fuel filter warning light means

Inside the fuel filter is a fluid level sensor that keeps track of the amount of water that has been collected. Once the level starts reaching maximum capacity, the fuel filter warning light will illuminate to let you know to empty the filter.

On manual systems, a valve at the bottom of the filter will let the water drain out once opened. If your filter empties automatically and the light comes on, it indicates that an error or malfunction has been detected and it needs to be checked out as soon as possible. This warning light could mean that the drain is blocked and the system can’t empty itself. A code will be saved on the computer to help you identify the cause of the problem. Have the car checked out with diagnostic scan tool to find the saved code or codes.

Don’t ignore this warning light or the system will fill with water and start leaking it to the engine. Once the water has been drained from the filter, this warning light should go out on its own.

Is it safe to drive with the fuel filter warning light on?

While it’s not an emergency when the light first comes on, it is important that you get the filter drained as soon as possible. Waiting too long will let the water build up and eventually let it get to your engine where it can cause some serious damage. Remember to change out the fuel filter at the right service intervals as draining the water will not remove all the particulates that are caught in the filter.

Our certified technicians are always available to assist you in diagnosing any problems with your car’s fuel filter and they can drain or replace your fuel filter for you.


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Matthew

32 years of experience
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Matthew
32 years of experience
Chevrolet Impala - Warning Light is on - Norfolk, Virginia
First off he was on time....actually 30 mins early which was great. Everything he described was what I was going through and he knew exactly what I needed before he even looked at the car. Other mechanics i feel were trying to take advantage because I am a woman but he made me feel comfortable. Still have to get work done on it but at least I know exactly what the problem was.
Chevrolet Tahoe - Warning Light is on - Norfolk, Virginia
Very detailed and takes the time to explain what is being done. Willing to answer any questions you may have. I would definitely use his services again and have already been telling my coworkers about this site. I have a unique electrical situation going on with my truck that none of the dealers could assess. Just by Matt doing some general maintenance , my truck is already driving smoother. Matt asked that I monitor things to make sure we don't need to troubleshoot anything else. I feel quite confident.

Quentin

18 years of experience
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Quentin
18 years of experience
Volkswagen Tiguan - Warning Light is on - Nottingham, Maryland
Quentin was very professional and meticulous with locating the issues with my car. Great spirit and explained and answered all of my questions.

Travis

12 years of experience
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Travis
12 years of experience
Mercedes-Benz C230 - Warning Light is on - Charlotte, North Carolina
Travis came out to determine cause for the Check Engine light. He did so and told me what needed to be done and the cost.

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8 years of experience
50 reviews
Juan
8 years of experience
Suzuki Grand Vitara - Warning Light is on - Durham, North Carolina
I won't go into details about the actual work performed - the result was completely satisfactory. Juan is knowledgeable about how these computerized engines work . He's very personable, polite, patient with my questions, and when I need service again, I'll request Juan. He put in more time than originally scheduled and seems to want to see things through and honest enough to tell you if the job is beyond his expertise and suggests taking car to dealer for more extensive diagnostic tests. I am well pleased.

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