P1131 Ford Code | Causes & Solutions

After starting up your Ford engine, you might see your engine light turn on if there are any issues. This could mean a number of things, so you should immediately do an OB II scan. In the OBD II scan of your Ford, a very common trouble code that shows up is the P1131. 

This code might seem very random to you, and you might not understand anything. To avoid this confusion, we will be talking about everything you need to know about the P1131 Ford code in our informative article. Without any further ado, let’s get right into the important parts!

P1131 Ford Code

What Does P1131 Ford Code Mean?

If the P1131 code shows up after you turn on your car, then it means there is an issue with the Oxygen sensor of your Ford car.

To go into more details, this code is shown when the O2 sensor bank 1 or sensor 1 doesn’t move sufficiently to lean. The Oxygen sensor does the job of determining whether the fuel to air mixture is excessively rich or lean by calculating the volume of the Oxygen in the mixture. 

This code means that the voltage of the O2 sensor has dropped lower than 0.45V because the mixture is getting too lean or too rich due to the malfunctioning sensor. If you didn’t know a mixture that is too lean has excess air and insufficient fuel, and one that is rich has excess fuel but insufficient air. 

Having a fuel mixture with the right fuel-to-air ratio is vital for your engine’s good health and optimum performance of your Ford vehicle. 

Codes that Are Associated with the P1131 Ford Code

Once you connect the OBD2 scanner and complete the scam some error codes can be displayed with P1131, and these codes can be related. Some of these codes are P1137, P1151, P1157, P1071, and P0174. You may be able to clear up some of these codes if you get onto fixing what’s causing the P1131.

What are the Causes of P1131?

The P1131 error could be displayed because of several causes, so let’s take a look at some of the major reasons to help you with the diagnosis of this issue. 

Blocked Air Filter

As you use your car, dirt can gradually accumulate in the air filter to the point where they are so dirty that the filters are completely clogged. This can prevent the flow of fuel from the filter during filtration. Because of this, the fuel mixture will become too lean, and the code will pop up. 

Defective Oxygen Sensor

As we have said above, the Oxygen sensor calculates how much oxygen is mixed into the fuel mixture. So, if the O2 sensor becomes faulty and adds too much or too little oxygen then the fuel-to-air ratio will be off. Therefore, the P1131 Ford code will be displayed after the scan. 

Faulty Air Mass Flow Sensor 

The job of the air mass flow sensor (MAF) is to calculate how much air is going into the fuel cylinder. Similar to the O2 sensor, if it begins malfunctioning, then the mixture will become either too lean or too rich. Consequently, you will see the error code. 

Problems in the Fuel System

The required volume of fuel that is needed to enter the combustion chamber may not enter if there is a problem with the fuel system. The malfunctioning of the fuel system could be a result of many parts including the pump, fuel filter, and injector. 

Malfunctioning Fuel Pump

Fuel needs to be delivered at the right pressure by the fuel pump so the mixture has an optimized blend. However, in the case of a faulty fuel pump, the pressure at which the fuel is delivered may be low which could make the mixture excessively lean. 

Components with Air Leaks

There are many parts in the engine, and all of them need to be in good condition for the engine to be running smoothly. However, over time some parts may have breakages which will cause air leaks. These air leaks will make too much air enter the cylinder, making the mixture too lean. Due to this, the P1131 code will show. 

Symptoms of P1131 Code in Ford

Symptoms of P1131 Code in Ford

There are many ways in which your car might be telling you that the P1131 code is there. Some symptoms are more visible than others, so we will be discussing all of them to help you recognize them before your vehicle gets damaged!

Engine Light On

Your engine light being on is the most obvious symptom of the     P1131 code in Ford. However, the engine light will be on for other codes as well. To check if the error code is P1131 or not, you will have to run the OBD2 scan. 

Hesitation while Accelerating

Your car may hesitate while accelerating for many different issues, including the P1131 code. There will be a drop in the performance of your Ford vehicle, and you will be able to tell that your engine is being more sluggish. 

Car Misfiring or Not Starting at all

Oftentimes when your engine has any problems your car may misfire, or in more severe cases it may not start at all. This is applicable when you have the P1131 Ford error code as well. You may see your car misfiring or not starting at all if things have gotten worse inside the engine. 

Fuel Economy Becomes Worse

When the fuel mixture does not have the optimized blend of fuel and air, then more fuel may be consumed than usual. Hence, there will be the overconsumption of the fuel and so your Ford’s fuel economy will get worse. 

Sudden Stalling

If there are issues in your engine that could trigger the P1131 code, then it could also result in your car suddenly stalling. This symptom is a clear sign that you should not continue driving your car, and should take it to a mechanic.

Knocking Sound from the Engine

It’s never a good sign when you hear strange sounds coming from your engine, and the engine knocking is also not something you should neglect. Amongst other things, this sound could mean that you would see the code being discussed after a scan. 

Is it Possible to Drive Around with the P1131 Trouble Code?

At times, you won’t notice any negative change in your Ford vehicle’s operation when you first notice the P1131 code. However, we would highly discourage you to drive around with the P1131 code for multiple reasons. 

Firstly, your engine’s performance will become worse and so you won’t be having the same power driving. Additionally, your car will noticeably hesitate when accelerating. Most importantly, you could be putting your safety at risk by driving with this error code. 

As you must know, your vehicle may suddenly stall or may stop starting if you have problems in your engine related to this code. This could be a huge safety risk, as your car stopping on the highway suddenly could result in an accident. Therefore, don’t be lazy, and get your car checked if the P1131 code has been displayed in your OBD II scanner. 

How to Diagnose and Fix the Code

Diagnosing, and fixing the P1131 code can be a very time-consuming process, and it essentially requires 4 tools: an OBD2 scanner, pliers, screwdrivers, and a wrench. 

Before you start looking for the source of the error code, check what other active codes are showing up after the OBD 2 scan, and clear them as per their saving order. You should also look for TSBs (technical service bulletins) for your specific Ford model. They can be very useful in clearing up such error codes. 

O2 Sensor

Address the most common source of the error first: a malfunctioning oxygen sensor. At first, you will have to locate the O2 sensor which is supposed to be around or on the exhaust manifold. After that, you need to check if it’s damaged. Keep an eye out for breakages, burnt areas, or any damaged spots. If it seems to be faulty then you will have to get the O2 sensor replaced. 

Air Mass Flow Sensor

If the O2 sensor seems fine, the next thing you should check is the air mass flow (MAF) sensor. To check whether this sensor is fully functional, you will have to use a scanning tool or a DVOM (digital volt-ohm meter). If the voltage is lower than what it should be then a replacement of the sensor is necessary. 

Cross Out All the Possible Causes

Besides checking these two sensors in the way that we have mentioned above, you will have to scratch off every possible cause for the P1131 code. For context, if you see that your air filter is clogged you will either have to clean it or get it replaced. Another example is if you notice any parts with leaks, you’ll have to get them fixed or changed. 

Keep on Doing the OBD2 Scan

With each fix you make, the following step should always be to do the OBD 2 scan. You will have to keep on repeating this until the scanner doesn’t display the P1131 code anymore. Rev up your engine, and see if the engine light is still on. If you have done everything properly, then all the warning lights should be off, and the active error code should be cleared. 

Tips to Avoid P1131 Ford Code

If you have encountered the P1131 code once, we’re certain that you don’t want to face it ever again. So, that you can avoid this trouble code in the future we have some tips for you:

  • Try to make time for taking your car to the mechanic for regular maintenance from time to time, to ensure you don’t bump into serious problems. 
  • Clean any blocked air filters.
  • Check the entire assembly. You should be keeping a close look at the fuel injector filters, and fuel pump
  • Get any damaged parts or wiring replaced immediately.
  • As soon as you have any air leaks get them fixed by sealing the broken part or get the component replaced. 

What is the Cost to Diagnose the P1131 Ford Code?

During the diagnosis, you need to buy any parts, so the only cost you have is the labor cost. You may think that you could diagnose it by yourself, but we wouldn’t encourage that. However, this labor cost is usually not cheap since the diagnosis can be a complex process. Diagnosing the P1131 code can take about an hour or two depending on the mechanic. The diagnosis process has a lot of common steps with the P1101 code in Chevy Cruze.

The labor cost will largely depend on the expertise level and location of your mechanic, but generally, it will be anywhere from $75 to $150 an hour. 


As you can tell, having the P1131 Ford code displayed on your OBD2 scanner can bring a lot of trouble your way. To avoid that, try to follow our tips on how to prevent it from happening in the future. If you’re someone who is currently struggling with this trouble code, we hope you have found our article helpful. 

Once you realize that you have the P1131 error code, you shouldn’t create any delays in getting to the workshop. Otherwise, you could be stuck with a severely damaged engine, or worse, injuries from an accident!

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