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Ford Focus Check Engine Light Diagnosis (Troubleshoot Guide)

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Diagnose and clear your check engine light!

We’ve scanned over 458272 Ford Focus’s with the FIXD OBD2 scanner and app. These are the 5 most common reasons for a check engine light in your Ford Focus.

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See how to easily find out why your check engine light is on and turn it off!
P0420MODERATE– Extended driving with this code can cause internal engine damageYour catalytic converter isn’t functioning efficiently. This could increase the output of harmful pollutants.
P1000LOW – Continued driving for a short period of time is okayYour car’s engine control computer has not completed its emission system testing
P0128LOW – Continued driving for a short period of time is okayThe recorded coolant temperature at the thermostat is lower than it should be.
P0171LOW – Continued driving for a short period of time is okayThere is either too much air or not enough fuel in the combustion chamber
P1450LOW – Continued driving for a short period of time is okayUnable To Bleed Up Fuel Tank Vacuum

When To Expect These Codes With Your Ford Focus

We’ve scanned millions of cars so we know at what mileage these common problems usually show up. Sometimes they happen sooner than expected or not at all, but these problems usually appear by the following mileages:

  • P0420 usually appears after 174996 miles
  • P1000 usually appears after 164076 miles
  • P0128 usually appears after 152307 miles
  • P0171 usually appears after 168468 miles
  • P1450 usually appears after 126248 miles

Check Your Gas Cap

One of the most common reasons for a check engine light in your Focus is also the easiest problem to fix. A loose gas cap is often the reason the check engine light turns on. This happens because the engine detects a leak in the evaporative emissions system, which exists when the gas cap isn’t tightened until it clicks. It’s easy, and it’s free!

What Should I Do If the Check Engine Light Is On in My Focus?

There are many issues that can trigger the Focus engine light, from a loose gas cap to major engine issues. If this light turns on, don’t panic. Check out our guide on what to do when your check engine light comes on. Following this guide can help you avoid driving with a serious problem and causing more damage to your engine. 

If you’d like some more information on diagnosing a check engine light yourself, you can also check out our article on the most common reasons for a check engine light.

For those of you who prefer a mechanic, you can find a trusted repair shop for inspection easily with RepairPal.

> Find a RepairPal Certified Shop Near You

What the Check Engine Light Means

Your Focus’s check engine light is part of the onboard diagnostics system (OBD2). All gas-powered cars and trucks made since 1996, plus diesel cars and trucks since 2008, have a diagnostic system to manage the engine and monitor emission system performance. It alerts the driver to any problems by turning on the Check Engine Light on your dashboard. Special tools known as OBD2 scanners or car code readers can access diagnostic information from this system to find out what’s wrong with your car and how serious the problem really is.

Instantly Diagnose Your Focus Check Engine Light

Read and clear over 7000+ check engine lights from your phone using the FIXD Sensor and free app!


How to Read Your Focus’s Check Engine Light

There are a few ways you can read the diagnostic trouble code stored in your car’s computer.

1) Go to your local mechanic. They will plug in their professional scan tool to read the code and identify the cause of the problem. This won’t help you on the side of the road, however, and they will charge a fee for this service. You also may not have a shop that you trust to diagnose the problem accurately, rather than try to make some extra money from repairs.

2) Go to a nearby auto parts store. Most parts stores will plug their OBD2 scanner into your car and give you the problem code and description at no charge. The person providing this service is likely not a mechanic, and may not be able to provide any more information than just the code and its technical description. It’s also possible that they may try to sell you products you don’t need in order to “fix” the problem.

3) Read your own check engine light codes with or without a scanner. Checking codes manually can be done but, it’s tedious. Borrowing a scanner or buying one makes the process easier. There are many OBD2 scanners you can buy that will read codes and provide other engine information anytime you want. FIXD is able to translate any Focus’s check engine light trouble code into plain English directly on your smartphone.

How the FIXD Check Engine Scanner Works

The FIXD car scanner plugs into your car’s OBD2 port. This is a trapezoid shaped plug located under the dashboard on the driver’s side of the car. You can read our detailed guide with illustrations on how to locate the OBD2 port in your car.

The FIXD Sensor and free mobile app will tell you in plain English what problem codes exist. You will get a detailed description of the problem so that you can make informed decisions about repairs.

Understand Your CEL

FIXD instantly translates over 7,000 error codes into simple terms right on your phone.

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See How Serious Your CEL Is

Learn if your problem is serious or not, and whether it’s safe to keep on driving.

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Get Maintenance Alerts

FIXD can automatically alert you when your Focus is due for an oil change and other routine maintenance, based on your specific model and its mileage.

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Monitor the Health of Your Focus

If your check engine light turns on, FIXD will immediately send a notification to your phone. You can also monitor data in real time, such as oxygen sensor voltage, fuel trims, vehicle speed, and more. Read this article to learn how you can use the FIXD scanner’s live data function to literally talk to your car when diagnosing most check engine light problems.

FIXD Monitor Car Health

Is It Safe to Drive with My Check Engine Light On?

That depends on what problem triggered the light to come on in the first place. You will need to use an OBD2 scan tool like the FIXD Sensor to find out exactly what’s wrong, how severe the issue is, and whether or not it’s safe to keep driving.

Generally speaking, if the indicator is a steady yellow light, it should be okay to keep driving.. This could be something like an emissions issue. While your car will keep running just fine, it’s still best to get this diagnosed and repaired sometime soon, especially if you live in a state that performs vehicle inspections.

If the light is blinking, you should stop as soon as it’s safe to do so. This indicates a serious problem, such as a misfire, that is occurring right then. It’s also good to check for low oil or overheating. If your Focus’s check engine light is red, you should stop driving immediately.

If your Focus experiences driveability issues, such as reduced power, slow down and take it easy on the engine to avoid making the problem worse.

How Can I Reset the Check Engine Light in My Focus?

If you have resolved the problem, you may want to clear the codes that triggered your Focus engine light. If you reset the light, drive, and it doesn’t turn back on, your problem is fixed.

The easiest way to reset the check engine light on your Focus is with FIXD. While auto parts stores will typically read your codes for free, they will not reset the light for you, and shops may charge more than $100 to do this.

In the FIXD app, you can reset the light anytime you want for free. After performing the engine scan, go to the Details page and click the “Clear Engine Light” button. The light will turn off, and any codes stored inside your Focus’s computer will be cleared. If the light turns back on after a few miles of driving, the issue likely still exists.

FIXD Clear Engine Light Button

Diagnose Your Focus’s Check Engine Light with FIXD

If the check engine light turns back on, use FIXD to get detailed engine diagnostics, plain English code descriptions, issue severity warnings, and so much more. Learn more about the FIXD Sensor and mobile app today!

FIXD Research Team

At FIXD, our mission is to make car ownership as simple, easy, and affordable as possible. Our research team utilizes the latest automotive data and insights to create tools and resources that help drivers get peace of mind and save money over the life of their car.

Clear your check engine light in seconds

The FIXD Sensor and free app tells you why your check engine light is on in easy-to-understand terms and lets you clear it with the touch of a button. 


We’re here to help you simplify car care and save, so this post may contain affiliate links to help you do just that. If you click on a link and take action, we may earn a commission. However, the analysis and opinions expressed are our own.


About the Author

FIXD Research Team

FIXD Research Team

At FIXD, our mission is to make car ownership as simple, easy, and affordable as possible. Our research team utilizes the latest automotive data and insights to create tools and resources that help drivers get peace of mind and save money over the life of their car.

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