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How to fix P0172 code: “System too Rich (Bank 1)”

How to fix P0172 code: “System too Rich (Bank 1)”

If you're searching for how to fix the P0172 code, this code indicates that your engine bank 1 is running with too much fuel. Too much fuel might be related to a lot of fuel supply or insufficient air supply. Whatever the causes, all you need to do is confirm the issue by using an OBDII scanner then, either clean the MAF sensor or replace the oxygen sensor. If none of these two methods fix your problem, you must visit the nearest repair shop to resolve the problem. 

Auto Repairs Are EXPENSIVE

Warning lights are very serious, even if they are linked to minor issues. Ignoring these lights can't complicate the problem and cause undesirable outcomes. Therefore, automotive experts never recommend ignoring a warning light.

As a driver, you need to know some of the common warning lights and error codes in your vehicle. For instance, the P0172 code is a crucial error code linked to your engine's air fuel mixture.

This article provides you with all you need to know about understanding the P0172 code, knowing the common causes and symptoms of a P0172 code. We also provide you with a rough estimate of how much it will cost you to fix the problem yourself or visit the mechanic.  

What is the P0172 code definition?

According to experts, the P0172 codes mean “System Too Rich (Bank 1).” If you don't have a certain level of mechanical skill sets, it can be extremely challenging for you to understand what it means when you simply read the P0172 code definition.

Therefore, it is crucial for you to understand how the fuel system works in your vehicle by referring to the basics we will cover in the next section. 

Air fuel mixture and its linkage to the P0172 code 

In any vehicle, the combustion system must receive a specific amount of air to fuel based on a certain ratio specified in your vehicle's manufacturer manual. Any disturbance in this ratio can affect the overall engine performance.

For example, if the engine receives more fuel than necessary, it's referred to as a vehicle is too rich. On the other hand, when the engine does not have enough fuel or receives too much air, it is a situation where you're dealing with poor fuel. 

In either case, your vehicle's overall performance will be affected. Some of them might also cause disturbance to the vehicle's overall fuel economy, while others might affect the engine's performance and the vehicle drivability to some extent. 

Whenever this happens, the engine's computer will send a signal to the vehicle's computer, which triggers the check engine light. Once you see the check engine light illuminating, it doesn't necessarily mean that it's and the only problem linked to the air-fuel mixture can be linked to a variety of other causes.

In the following sections, we will show you how to determine whether the check engine light is related to a problem with a P0172 code or not. 

What are the primary causes for the P0172 code?

The P0172 code might be triggered do too a variety of reasons, including:

  • Issues with engine oil contamination
  • Problems with fuel injector leaks
  • Troubles with high fuel pressure might affect the flow of fuel in the tubes
  • Issues with packing fuel tank resulting in a saturated carbon canister 
  • Clogs in any of the exhaust components, including the muffler, the exhaust pipe, and the catalytic converter 
  • Issues with the oxygen sensor 
  • Leaks in the exhaust system
  • Troubles with the PCM, which needs an update in the software in most scenarios 

How do I know if it’s the P0172 code? Symptoms of the P0172 code

When your vehicle has an issue related to the P0172, there are clear symptoms that you can keep an eye for to help you detect the problem earlier, including:

  • Check engine lights illuminating 
  • Vehicle running rough
  • Issues with a reduction in fuel economy
  • Clear fuel smell, especially close to the exhaust system
  • Engine misfiring
  • Reduction in engine power 

Keep in mind that all mentioned symptoms can be related to a variety of other issues. Therefore, you cannot simply rely on a check engine light illuminating to say that your problem is linked to a P0172 code. Similarly, engine misfiring is not always a problem due to an issue with the P0172 code.

Therefore, before attempting to resolve the P0172 code, you need to confirm the problem, and the quickest and most accurate way to do so is by using an OBDII scanner. 

P0172 code diagnostics

The good news is that the P0172 code can be easily diagnostics from home, so you don't really need to go to the mechanic and pay a lot to understand whether you have a P0172 code or not.

To do so, you need to use an OBDII scanner tool. This tool is basically a scanner to connect to the vehicle and read the error codes from the vehicle’s computer. Usually, their code is displayed on the screen as a code and a small text description. In some advanced OBD tools, you might even get some information about repair options and repair costs.

As we always say, you don't need to purchase the most expensive OBDII scanner because you won't need it frequently as compared to a professional mechanic who will use it on his daily basis. 

Once confirming the error, it basically indicates that the bank on one side of the engine has a lot of fuel and the fuel is more than the air. It could also mean that there is no sufficient air in the air-fuel mixture at this side.

 How do I fix the P0172 code?

Luckily, there are some DIYs that you can try at home to fix the P0172 code. Sometimes these methods might work successfully. However, they might not solve the problem completely, and that's when you need to visit the nearest repair shop to get the problem resolved.

According to experts, here are the common two DIY's that you can try whenever dealing with a P0172 code

  • Inspect the MAF sensor 

The MAF sensor might be the culprit causing the P0172 code. Therefore, you need to locate the sensor, usually located between the air filter and the throttle body. If you can't find it easily, you can always refer to your vehicle's owner’s manual, giving you detailed guidance on where to find the MAF sensor. 

Remove the MAF sensor carefully and use a MAF sensor cleaner to clean any clogs or the breeze stuck in the sensor. It is very important to clean the sensor as you're holding it vertically to allow the spray to drop on the floor to damage the sensor. 

Once the MAF sensor is completely dried, you can go ahead and reinstall it. Test your vehicle and see if you still have the P0172 code. Keep in mind that the code will not be cleared out by itself, and you must use the OBDII scanner to check for any act of errors because the air will still be there even if it's not active. 

  • Inspected the oxygen sensor 

The second thing you need to check with a P0172 code is the oxygen sensor. It is usually located close to the exhaust manifold. If you still have issues finding it, you can always refer to the vehicle's owner’s manual to get a detailed description of where it should be located. You can also watch any YouTube videos or look for images through the Internet for directions on finding the oxygen sensor of your vehicle. 

You were once locating the oxygen sensor, disconnected from the catalytic converter, and refer to your manufacturer to get an identical oxygen sensor. Install the new sensor and give your figure a test drive. Look at the vehicle's errors and see whether the P0172 code is still active or not.  

Will the P0172 code clear itself? 

Unfortunately, the P0172 code will not clear itself after fixing the problem like any other error code. Therefore, you need to use an OBDII scanner and connected it to the vehicle. Once you connected to the vehicle, ask the scanner to rescan the car. You should see an inactive error saying P0172. You can go ahead and ask the tool to clear this error so you can get rid of it permanently. 

Again, ask the tool to scan the vehicle to ensure that there are no other issues or confirm that you fixed the problem of the P0172 code. 

Can I drive my car with a P0172 code?

Unfortunately, when the P0172 code is triggered, you won't be able to drive your car for long distances.

While you will still drive the car for short distances, ignoring and delaying the repairs can introduce major damages to one of the most expensive parts of your car, the catalytic converter.

Whatever reason preventing you from fixing the P0172 code should not be as important as dealing with catalytic converter repairs. Did you know that the Catholic converter replacement cost can get up to $3000, if not more, in some vehicles? Who wants to deal with that?

Therefore, immediately after noticing any of the symptoms of a P0172 code, you must take your vehicle to a professional mechanic to resolve the problem if none of the DIY's listed in this article worked for you. 

How much does it cost to resolve the P0172 code?

Of course, answering this question depends heavily on the primary cause for triggering the P0172 code. In most scenarios, the problem usually is related to an issue with the oxygen sensor, which is not a complicated problem. Usually, replacing the sensor should not cost you more than $60.00.

However, if the problem was left for a longer time frame, you might introduce them into the catalytic converter, which can cost you easily up to $3000 if not more in more modern vehicles. 

Those, we always recommend whenever you notice symptoms of a P0172 code is to fix the problem either yourself or by visiting a professional mechanic. 

Keep in mind that fixing a P0172 code involves labor costs which can be significantly different when you go to a dealership versus when you go to a small repair shop. Sometimes owners of modern vehicles prefer to go to the dealership even if it will cost them more because they will be more confident that advanced and experienced mechanics will be working on fixing their problem. Therefore, there is very limited chance for introducing major issues to the catalytic converter or any of the surrounding components. 


The P0172 code indicates that there is more fuel that air in the bank one side of your engine. It is important for your car to have the right air fuel mixture ratio to operate properly.

It is important for you as a driver to take care of the P0172 quote immediately to prevent dealing with major repair costs that might get you up to $3000 if not more one of our needing to replace the catalytic converter.

This article provided you with all what you need to know about the P0172 code including the main causes, symptoms, along with suggested repairs and expected repair costs.

If you notice that the P0172 code is linked to a major problem like issues with the catalytic converter, it might be the right time now to evaluate whether it's worth selling your car to Cash Cars Buyer or not. 

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