P0171 Code Causes and Fixes - Fuel Trim System Too Lean | JEGS (2024)

Whether you're enjoying a Sunday afternoon drive or spinning tires at the track, the last thing anyone wants to see is the Check Engine Light. Without any symptoms or an OBD II reader, it's hard to know what's causing the Check Engine Light. However, once you check the code and it reads P0171, it's time to have the problem addressed fast because it means your engine is running too lean.

When your engine is running too lean it's getting too much air and not enough fuel. Running an engine in this state will lead to misfires, cylinder damage, and damage to your pistons. A plethora of other problems are also possible, so make sure you address them immediately.

Read on to learn everything you need to know about engine code P0171.

What Is the P0171 Code and the Symptoms?

The P0171 engine code is a code that produces a Check Engine Light on your dashboard. It's your vehicle's Power Control Module (PCM) notifying you that your engine is running too lean in bank 1.

When it comes to engines, bank 1 is usually the one that has the front-most cylinder. Additionally, bank 1 will be on the left side of your engine when you're looking at it from the front end. It's also important to note that many vehicles only have one bank. For example, engines that have bank 2 are usually only V6s, V8s, V10s, or V12s.

Typically, the P0171 engine code is also paired with a P0170 code; the P0170 code states that there is an issue with the fuel trim.

What Are the Symptoms of the P0171 Code?

There are a handful of symptoms you'll notice if you get a P0171 reading. However, some of these symptoms may be hard to notice if you're not paying close attention.

We list some of the most common symptoms below:

• Engine running with a lack of power or acceleration
• Rough idle
• Stalling at traffic stops
• Pinging or knocking sound coming from the engine
• Trouble starting the engine
• More fuel consumption

When you notice these symptoms, accompanied by a Check Engine Light, there's a good chance that you're dealing with a P0171 code.

That said, some of these symptoms may also appear with P0170 or P0172 codes. The P0170 code states that there is a fuel anomaly and the P0172 code is the opposite of the P1071 code, which means your engine is running too rich.

How Serious Is P0171 and What Are the Causes?

The P0171 engine code is serious. Whenever your engine isn't getting enough fuel, you'll experience a loss of power, stalling, and improper combustion. Additionally, you may damage your catalytic converter and spark plugs. These problems can put your life in danger and cause severe damage to internal components like the pistons, piston rings, and cylinder heads.

Understanding the cause of a P0171 engine code can help you prevent the problem from happening or improve your chances of identifying the solution.

See Also

Code P0171 - System Too Lean: Symptoms, causes, common problems, diagnostic

Problems With Your Fuel System

One of the most common causes of the P0171 engine code is a fuel system leak. When your fuel system leaks, more air and less fuel will enter the engine's cylinders. This results in your engine running lean because it can't get the necessary amount of fuel.

Another problem with the fuel system is clogged fuel injectors. Modern vehicles use fuel injectors to spray the perfect amount of fuel into the cylinders but when these injectors are clogged, more air than fuel can enter the cylinders. This may result in misfires and a P0171 engine code.

The last thing to note about the fuel system is the fuel pump. A bad fuel pump may not pump enough fuel into the fuel lines, which will result in less fuel entering the cylinders.

Faulty Sensors

Most engines rely on sensors to ensure that the right amount of fuel and air enter the engine. Some of the most important sensors for this process include the mass airflow sensor and oxygen sensors. If either of these sensors is dirty or defective, your engine may run too lean. You'll also find a Check Engine Light accompanied by a P0171 code or P0170 code.

While these are the most common causes of a P0171 engine code, they're not the only ones. You'll also need to keep an eye on your exhaust system for any leaks.

Can I Still Drive with a P0171 Code on My Car?

Yes, you can still drive your car with a P071 code. However, that doesn't mean that you should. Driving with a P071 code is dangerous for you and the vehicle, especially if you're stalling at traffic lights or while you're driving. Furthermore driving with a P0171 engine code may cause damage to internal engine components that result in expensive repairs.

Ignoring a Check Engine Light and a P0171 engine code is always a bad idea, even if you suspect it's just a faulty sensor. Always have your vehicle inspected to ensure that everything is running fine. Otherwise, you'll end up with damaged fuel lines, misfires, fuel pump damage, and several other costly problems.

How Can I Diagnose a P0171 Code?

Diagnosing a P0171 code in a Chevy vehicle or any other vehicle by using an OBD II scanner. These are tools that you connect to your vehicle's computer. Usually, the place to connect the scanner is under the driver's side dashboard. When you have a Check Engine Light you can use the scanner to identify the engine code. If it's the P071 code, then you know your engine is running too lean.

While your engine may display a code P0171, that doesn't always mean there is an issue with your vehicle. In fact, you might be dealing with faulty sensors. For this reason, reading the code is not always enough. Always check the sensors and bring your vehicle to a technician if you don't know how to replace parts under the hood.

The good news is that if you're dealing with a sensor problem replacing them is all you need to fix the problem. In most cases, this means replacing a faulty air-fuel sensor or O2 sensor.

How Difficult Is It to Inspect a P0171 Code?

It's always best to consult with a professional when dealing with a P0171 engine code. For someone who's not a technician, it's sometimes challenging to check and address this problem.

Inspecting a P0171 code begins with checking the fuel system. You'll want to check for any problems with the fuel injectors. It's important to look for any clogs or issues with the fuel pump as well as any problems with the fuel lines. If anything is broken or if there is a vacuum leak, it needs to be repaired to fix the code.

The last step is to disconnect and clean the mass airflow sensor. Then, check to see if the Check Engine Light has turned off. If it hasn't, you'll want to start checking other areas of the vehicle. Look for issues with the exhaust system and other oxygen sensors. Replacing these sensors may be necessary to remove the P0171 code.

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