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DISCLAIMER: AS AN AMAZON ASSOCIATE I EARN FROM QUALIFYING PURCHASES. THIS POST CONTAINS AFFILIATE LINKS THAT WILL REWARD ME MONETARILY OR OTHERWISE WHEN YOU USE THEM TO MAKE QUALIFYING PURCHASES. FOR MORE INFORMATION, PLEASE READ MY EARNINGS DISCLAIMER.

If you are wondering if brake fluid can cause the Check Engine light to come ON, the answer is NO, brakes have their own warning light (which is an exclamation mark in a circle). Check Engine light only alerts you of engine-related problems or open gas cap.

The brake light, on the other hand, will warn you of a low brake fluid problem. If you think that you don’t have enough brake fluid in your system, you should NOT drive your car and get it towed to the nearest mechanic!

Your braking system will NOT work if you don’t have enough brake fluid and that has nothing to do with the Check Engine light coming ON. Flashing the Check Engine light is more of a problem than a steady ON light.

Here is a good article on flashing Check Engine lights. The reasons for Check Engine light sometimes are very simple to take care of (like a gas cap that is loose) and some will require a professional to take a look.

Here is a list of common reasons behind the Check Engine light:

  • Loose gas cap.
  • Failing oxygen sensor
  • Failing spark plugs or their wires
  • The catalytic converter is getting damaged
  • The Mass Air Flow sensor (MAF) went bad

If the reason why you actually thought of the low brake fluid being the problem of your Check Engine light coming ON, is that you are actually having some problems with brakes, you should NOT ignore it and have a professional check it out!

Brakes on the car are NOT something you should take lightly. Some people wonder WHY are they able to use them when the brake fluid is low, and the answer is that:

It is NOT low enough now, but it will be!!!

If you have a brake fluid leak, or simply noticed that some of it are missing, you will have a PROBLEM soon, so don’t drive like that!  You NEED brake fluid in the lines and wheel cylinders in order for your brakes to work.

If you drive with low brake fluid, you are risking getting air into the brake lines and your brakes start getting worse and worse. You will also have a problem with your brake pads wearing out more quickly.

The brake fluid is a medium that allows pressure from your foot to be transferred to the wheel cylinders through the brake lines by the master cylinder. As wheel cylinders expand, the brake gets activated.

Without this pressure, your brakes will not be able to stop your car! One reason behind low brake fluid levels is a leak. If you have a leak, since the brake fluid is most of the time under pressure, the liquid will disappear very quickly as the brake system is used.

Do NOT attempt to drive your vehicle with LOW brake fluid!

The good part, it is not very difficult to notice that you have a problem with your brake liquid, and here are some clues:

  1. Brake or ABS light illuminates
  2. Brake fluid is dirty or discolored
  3. The brake pedal becomes “mushy” or “spongy”
  4. You have problems stopping!

The reasons behind your low brake fluid problem could be any of the following:

  • A leak. It could be located anywhere in the braking system, including lines, hoses, calipers, or the master cylinder. Having a leak is dangerous because it reduces the hydraulic pressure needed for you to stop the vehicle. The leak could come from hitting something harsh on the road or normal wear and tear. You will generally notice a residue left underneath your car.
  • Worn out brake pads. Driving with worn-out brake pads will result in brake fluid being used more and depleted faster. Over time it will be getting less and less.
  • Damage in the brake line. Brake lines are subject to wear, tear, and rust. This is especially true if you drive very often on salty roads in winter.

Feel free to read this article on how to recognize a low brake fluid problem.

Besides taking care of your brakes, you still need to figure out what has caused the Check Engine light to come up.

The easiest way to do it is to get an OBD-II scanner and troubleshoot the problem. Everyone needs one of those gadgets in a car and they are conveniently sold on Amazon (paid link).

Code examples:

  • P0577. Pressure problem within the brake booster.
  • P0556. No voltage input from the brake booster pressure sensor.
  • U0121. Lost communication with ABS control

Check Engine light typically means that you have a problem with the emissions control system. It is also DIFFERENT from the Engine Maintenance (or Service) light, which means that your routine service is due.

There is also a variety of situations where Check Engine light means DIFFERENT thing:

  1. You Check Engine light is FLICKERING. If your Check Engine light is intermittently flickering (as opposed to the more serious condition mentioned below as FLASHING), and it is happening in the slow driving conditions, then you still have a chance to get home safely and inspect your vehicle. If you notice that driving feels different when this light comes ON, then take it to the service station to get checked out.
  2. Your Check Engine light stays ON. If you still have no noticeable problems with your car, your computer is “telling” you to get your car home and get it serviced as soon as you can. Driving too long with the Check Engine light ON is NOT recommended, since it can cause irreversible damage to your emission control system.
  3. Your Check Engine light is ON and you have performance problems. This is a very serious condition and it is not safe even to drive your car home. Call the nearest mechanic and tow your car. It is also possible that “safe mode” or “limp mode” got activated in your car and you now have a problem with acceleration.
  4. Your Check Engine light is steadily FLASHING and/or you have acceleration problems. This means that your engine is misfiring and your catalytic converter is failing. Immediate action is required at this moment from you and you should NOT drive any further. Call a tow truck and get your car serviced before any more damage to the catalytic converter is made!

This article is for informational purposes ONLY and is NOT a replacement for professional advice!


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