ford auto start stop feature

Ford Auto Start Stop Not Working [Causes & Fix]

One of the common questions I get from Ford owners is why their automatic start-stop system isn’t working.

There are a number of possible causes for this issue but in this article, I am going to share with you the most common causes for this issue as well as provide you with a few simple fixes based on my knowledge as a mechanic.

What is Ford Auto Start Stop Feature?

Before I get to what causes the automatic start-stop system to malfunction on your Ford, it is important to understand what this is and how it works.

In simple terms. the auto start stop feature is a system that automatically switches your engine off when you are idling for an extended period of time.

The system will turn on the engine again once you take your foot off the brake pedal and step on the accelerator. This feature is designed to save fuel and reduce emissions by preventing unnecessary idling.

In order for it to work properly a certain number of conditions need to be met, these include:

  • Battery charge must be at least 70% or more
  • Your Ford engine must be warm
  • All Doors need to be closed
  • Driver’s and Passenger’s Seatbelts must be fastened
  • The outside temperature is not below 4 degrees Fahrenheit

What Causes Ford’s Auto Start Stop Not to Work?

Now, that I have briefly explained what this feature is and how it works, let’s look at some of the common reasons why it may not be working.

Low Battery Voltage 

As an auto technician, I have found that low battery voltage is the most common reason why your Ford auto start stop may not be working.

The start stop system requires at least 70% of your battery’s charge to be able to function correctly.

If the battery voltage drops below a certain level, your Ford’s Battery Management System (BMS) starts to limit some functions in order to prevent the battery from draining completely.

If you haven’t been driving your car for a while, the battery may not have enough charge for the start stop system to work.

Bad Battery

If you drive your Ford enough for the alternator to properly charge the battery but you have a bad/failing battery then your Ford auto start stop won’t work.

The main reason for this is an old battery that has lost its ability to hold a charge.

The alternator will only be able to charge the battery enough for basic functions, like the lights and radio, but not enough for the start stop system to work properly.

If your car’s battery is older than 4 years then it may be time to replace it with a new one.

Other Possible Causes

Although I would say 90-95% of the time that a bad battery or a low battery voltage will cause the Auto Start Stop to not work, there are other possible causes as well. These include:

  1. Bad Wiring
  2. Failing Alternator
  3. Blown Fuse
  4. Damaged Start Stop Relay
  5. Extremely Low Outside Temperature

How to Fix a Ford’s Start Stop System that is Not Working

Finally, let us take a look at how to fix Ford’s start stop system that is not working.

1. Charge the Battery

The first thing you should do is charge the battery. you can charge your vehicle battery by:

Driving a few miles:

The best way is to drive the car for a few miles. It will help re-establish the battery’s charge, which can fix many electrical problems. when you drive your car, it allows the alternator to charge the battery.

Use a Portable battery charger:

The second option is to use a portable battery charger.

This will allow you to recharge your car’s battery without driving it anywhere.

It is a great option for those who don’t have time or drive shorter distances.

Remember in order for the start-stop system to work properly, the battery charge must be at least 70%. If your battery is too low, the start stop system will not function.

2. Replace the Battery

If you drive your Ford frequently for the alternator to charge your battery enough then the issue might be caused by a failing battery.

The battery on your Ford will typically last anywhere between 3-5 years and will require replacement if it is no longer holding a charge as it should.

If this is the case, the best option is to replace your battery with a new one this should fix the auto start stop problem.

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