Tag Archives: Check Engine Light

What does Wrench Light on Ford vehicles mean?

Late models of Ford, especially AWD or 4WD vehicles have the warning light that is amber and shape of a wrench. The wrench light on Ford vehicles is a powertrain malfunction indicator light. When the vehicle computer detects a problem on the engine or transmission, it turns on the wrench light and restricts the vehicle performance.

What does the wrench light mean?

The meaning of the wrench light roughly the same as the check engine light. When the computer detects on the engine or transmission, it turns on the wrench light. You may see the check engine light on at the same or later on.

What is the difference between Check Engine Light and Wrench Light?

Two indicator lights have many things in common. They may illuminate at the same time. The difference is that the wrench light is a part of the Ford manufacturer’s own warning system while the check engine light is a part of On-Board Diagnostics (OBD) system that is standardized on all vehicles manufactured in the U.S. of the model year 1996 and later. And the wrench light indicates the related problems limited to throttle control and transmission.

What to do when the wrench light comes on?

First of all, you may not have many choices other than pulling over because a vehicle may be heavily restricted acceleration or shifting on transmission. What is important is what to do after pulling over the vehicle.

The computer most likely store the diagnostic trouble codes (DTCs), even if the check engine light isn’t on. Pending codes don’t turn on the check engine light. If you have an OBD scan tool, get the codes. If you don’t have one, go to a local parts store, and they may scan the computer for you for free. Your vehicle may be in the condition that is too hard to get to the stores because of reduced engine power. In that case, turn off the engine and restart after a while, and the wrench light may disappear, and your car may start and drive as if nothing has happened. However, as long as the problem exists, the light will come back on. So, it’s important to scan the computer and get the DTCs as soon as possible.

If restarting the engine fixes the problems temporarily, you may perform self-diagnosis as long as you are comfortable to do so. It means that you can try to find when exactly the wrench light comes on. For example, you do this a couple of times and find out that the wrench light comes on every time the car shifts to the 3rd gear. From this, you can guess the cause of the problem would be in the transmission. Even though you’re not a DIYer, this information will help a mechanic diagnose and fix the wrench light problem.

If you are considering buying an OBD scan tool, please note that most cheap OBD scan tools aren’t capable of reading the pending codes and the manufacturers specific codes, (B-codes, C-codes, or U-codes, neither.) In my experience, most of the time, the wrench light comes with the manufacturer’s specific codes, which start with P1xxx. So, you will need a good one. It used to be that only professional-grade scan tools which cost thousands of dollars could get all these codes. But now you can buy one for a fraction of costs. BlueDriver is an OBD scan tool that works with a smartphone’s app. For selected manufacturers including Ford, you can get all these codes.

Getting DTCs is one thing you must do when the wrench light comes on, and checking an electronic throttle body (ETB) is another, especially your vehicle has a lot of mileage. A carbon build-up and sticky gunk inside the ETB can affect the movement of the throttle plate and confuse the computer finding the right throttle position. When it happens, the computer turns on the wrench light and puts the engine into the limp home mode. So, if it’s dirty, clean up the ETB with an appropriate cleaner and perform the idle relearn procedure.

Read Also: How to clean the Throttle Body?, Ford Idle Relearn Procedure

Don’t confuse with the oil change reminder light

image of 2011 ford fiesta wrench light and oil change reminder light

Some people confuse the wrench light with an oil change reminder light. Many YouTube videos show how to reset the oil life on Ford vehicles. But a few videos mistakenly treat the wrench light as the oil reminder light. The videos show how to reset the oil change reminder light correctly. But these two lights have a totally different meaning. One is a warning light, and the other is just a reminder light. Only a few models and years have this indicator light. As long as I know, they are Ford Fiesta 2011, 2012, and 2013. Other models and even newer models of Fiesta don’t have one. Instead, most Ford vehicles remind you by showing the message “Engine oil change due” on the information display. The procedures of resetting the oil life are almost the same.


The wrench light is a powertrain malfunction indicator light. When it comes on, you may experience a severe reduction in the vehicle’s performance. The causes of the problem lie on throttle control and/or transmission. The light may come on along with the check engine light. Whether the check engine light is on or not, get the codes with a good OBD scan tool and narrow down the possible causes of the problem. You also need to check inside of the throttle body. If it’s dirty, clean it up and perform idle relearn.

Where can you get Free Check Engine Light Diagnosis?

Check Engine is one of the indicator lights in the instrument panel and also a part of On-Board Diagnostic system aka OBDII. When there is something wrong in the engine or emission system, the vehicles computer turns on the Check Engine Light to notify the driver. At the same time, the vehicle computer stores the code(s). You can see the codes by scanning the vehicle computer with a scan tool (also called a scanner or code reader.) Scanning the computer is the first step of check engine light diagnosis. And you can get free check engine light diagnosis in some ways

image of check engine light

Auto Parts Stores

Here is a list of auto parts stores that offer a free computer scan and tell you the codes. These are not all stores but my local stores I verified.

  • Advance Auto Parts
  • AutoZone
  • Napa Auto Parts
  • O’Reilly Auto Parts
  • Pep Boys Auto Parts

The reason why they do it for free is that it’s not technical job. What they do is to plug a scanner into an OBD port and press a few buttons, and they get the codes.

But still, why do they do that for free?

First of all, they are not repair shops but parts stores. I guess they are hoping you to buy the parts at their stores to fix the check engine light problems for yourself. They may even mention the common causes of the problems of the specific code. For example, the code P0136 is O2 Sensor Circuit Malfunction Bank 1 Sensor 2. A store clerk may mention that a bad oxygen sensor can be the cause. Sometimes, it’s true, but not always. Keep in mind that you can’t assume the cause of the problem without further diagnosis.

Local Mechanic Garage

If you have a good relationship with your local mechanic, they may scan the computer for you for free. But that’s all they offer for free. Unlike parts stores, mechanic garages fix the problem. They are capable of identifying the cause of the problem with further diagnosis. This diagnosis incurs a fee for labor of at least an hour. So, if you go to a mechanic garage, tell them that all you need is to have the computer scanned, and make sure if they do that for free in advance.

Scan for yourself

It’s not exactly free because you have to buy a scan tool, but it’s recommended for a DIYer. The prices of scan tools range from $20 to thousands of dollars. You can get a decent one for around $50. Once you bought one, you can scan the computer as many times as you need. You can freely use other features like clearing the check engine light, I/M readiness monitor, live data, and so on. BlueDriver is one of the most popular scan tools. Unlike conventional scan tools, BlueDriver is a Bluetooth adapter that connects with your smartphone and works with the app. It has advanced features like enhanced diagnosis (ABS, SRS, TPMS, etc.), Mode 6, Repair Report, and so on. Click here to see the details of BlueDriver.


Scanning the computer and getting the codes are the first step of tackling with check engine light diagnosis. With the codes, you can look up the details, possible causes, and possible fixes on the internet. In the end, you may still have to go to a mechanic garage to fix the problem, but it’s good to have some insight about the problem beforehand. If they tell you something unrelated to your research, you should ask for more details about that. You also have an option to go to another mechanic garage for a second opinion.

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OBD Diagnostic Codes Explained

The check engine light comes on, and you can scan the vehicle’s computer and get OBD diagnostic codes. The codes don’t tell you which part is needed to replace. They just tell you that the symptom of the problem and you will need to diagnose further to determine the cause of the problem.

image of obd scan tools

The codes consist of one alphebet and 4-digit number. Without looking up the meaning of the code, you can tell some information from the alphebet and the first 2 digit.

The codes are categorized into four different types. B is for Body, C is for Chassis, P is for Powertrain, U is for Network. P-codes are responsible for check engine light. The P-codes starting with 0 are generic codes. They are standardized. It doesn’t matter which manufacturer. The code starting with 0 are the same meaning among any manufacturers. However, the P-codes starting with 1 are manufacturer specific codes or enhanced codes. These codes have a different meaning for each manufacturer. Some cheap code reader can pull out the codes but without descriptions. You will need to look up the meaning of the codes online or repair manuals.

The second digit of P-code tells you the following categories. You don’t have to memorize them, but it’s good to know that they are categorized into those systems.

  • 1 Fuel and Air Metering
  • 2 Fuel and Air Metering Injector Circuit
  • 3 Ignition System
  • 4 Emission Controls
  • 5 Vehicle Speed Controls and Idle Control
  • 6 Computer Output Circuit
  • 7 Transmission
  • 8 Transmission
image of bluedriver

Now you have a better idea of OBD diagnostic codes. You can tell which system is having the problem from the codes. Then you will have to diagnose further to narrow down the cause of the problem. An OBD scan tool called BlueDriver is a very popular OBD adapter. It is focused on vehicle diagnostics. You will get the detail of the codes and repair reports that contains possible causes and verified fixes. And it can scan enhanced codes including ABS, SRS, Transmission, TPMS, etc. With a good repair manual, you can tackle complicated OBD-related problems with confidence.

Read Also: What should you do when Check Engine Light comes on?

What should you do when Check Engine Light comes on?

Check Engine Light is a little amber light on the dashboard. Depending on models, it can be just the word Check, Check Engine, or Service Engine Soon, or the icon of a small picture of the engine, or the combination of the icon and the word. By illuminating Check Engine Light, the vehicle computer notifies the driver there is something problem with your car. Instead of just taking your car to a mechanic, let’s see what you should do when Check Engine Light comes on.

What is Check Engine Light?

Check Engine Light is a part of the Onboard Diagnostic system. When the vehicle computer detects abnormality from one or more of various sensors. It tells you that by illuminating Check Engine Light. At the same time, the computer stores a trouble code(s), which gives you a rough idea of the problem and where to start diagnosing.

Trouble Codes

Trouble codes are sets of one alphabet and a four-digit number. The alphabet shows which system of the vehicle a problem exists, and the four-digit number shows the details of the problem. P-codes are responsible for Check Engine Light to come on. P stands for Powertrain, which is the category including engine, transmission, and associated drivetrain.

What to do when Check Engine Light comes on

Most of the cases, Check Engine Light doesn’t mean that you have to pull over and stop the engine and call a tow truck. But, you need to pay attention and have your car diagnosed as soon as possible.

Some cases, however, you need to take your car to a repair shop right away. When Check Engine Light is flashing, the engine is misfiring. You probably notice the engine shaking and losing its power.

If you don’t notice any performance change and it illuminated all of a sudden, it’s worth checking a gas cap. Sometimes, a loose gas cap can be the cause of check engine light. Some vehicles even have a separate indicator light for the purpose. Let’s say it was actually loose, and you tightened it. Check Engine Light doesn’t go off right away. It requires several drive cycles to clear the light.

Scan, get the code

Now, it’s the most critical part. Ever time you have Check Engine Light on, you should scan and retrieve the code which triggered Check Engine Light to come on so you can look up the detail of the problem from the internet or repair manuals.

Some repair shop will scan the computer for free. You may want to stop by such repair shops and have a trouble code retrieve.

Scanning the computer and retrieve the codes are not a technical job. Anyone can do it. If you want to do it for yourself, you can have your own scan tool. A pocket-size code reader costs $20 to $50, and you can store it in the glove compartment. Some other favorite items are OBD adapters. They are just adapters to be plugged into an OBD port and connected to your smartphone wirelessly. Then, you navigate with smartphone’s app. These adapters cost $20 to $100.


Check Engine Light doesn’t mean that you have to pull over immediately and call a tow truck. But, you need to know what code triggered the light to come on. Even if you don’t know much about a car, it’s important to retrieve the code and take a memo of it so you can look up the details or ask someone else for advice. Whether you fix the problem or ask a mechanic to fix, it’s good to have your own scan tool always in a glove compartment.

Read Also: OBD Diagnostic Codes Explained