The P0171 error code is a common diagnostic trouble code (DTC) that can occur in most cars. It indicates that there is a problem with the fuel system, specifically, that the fuel mixture in the engine is too lean.
This code is generated by the onboard diagnostic (OBD-II) system of a vehicle and can cause the check engine light to come on.
What causes the P0171 error?
The cause of the P0171 error code can be a variety of things, including a faulty oxygen sensor, a clogged fuel injector, a dirty mass airflow sensor, or a vacuum leak. In some cases, it can also be caused by a failing fuel pump or a fuel pressure regulator. These components are responsible for regulating the fuel system and ensuring that the engine receives the proper amount of fuel.
Common symptoms of the P0171 error
The P0171 error code can cause a variety of symptoms, depending on the severity of the issue.
Here are some of the most common symptoms associated with this error code:
- Check Engine Light: The most obvious symptom of the P0171 error code is the illumination of the check engine light on the dashboard. This light indicates that there is a problem with the vehicle’s emissions system.
- Poor Fuel Economy: A lean fuel mixture caused by the P0171 error code can lead to poor fuel economy. You may notice that your vehicle is getting fewer miles per gallon than usual.
- Rough Idling: A lean fuel mixture can cause the engine to idle roughly or even stall.
You may notice that the engine is shaking or vibrating more than usual at idle.
- Hesitation or Stumbling: A lean fuel mixture can cause hesitation or stumbling when accelerating. You may notice that the engine is slow to respond when you press on the gas pedal.
- Engine Misfires: A lean fuel mixture can cause the engine to misfire, which can be felt as a loss of power or jerking sensation while driving.
- Exhaust Smell: A lean fuel mixture can cause the exhaust to have a strong smell of unburned fuel.
If you are experiencing any of these symptoms, it is important to have your vehicle diagnosed by a professional mechanic to determine the cause of the issue and prevent any further damage to your vehicle.
Diagnosing the P0171 error code
Diagnosing the P0171 error code can be done with the help of a diagnostic scanner. This tool can read the DTC stored in the OBD-II system and provide information about the specific issue causing the code.
A mechanic can use this information to perform a visual inspection of the components involved in the fuel system and determine the cause of the issue.
To further diagnose the problem, a mechanic can perform a fuel pressure test, a vacuum test, or an exhaust gas analysis. These tests can help determine if the fuel system is providing the proper amount of fuel, if there is a vacuum leak, or if there is an issue with the oxygen sensors.
The cost of diagnosing the P0171 error code can vary depending on the make and model of the vehicle. The following table shows the estimated cost of diagnosing this code in different car brands:
| Car Brand | Estimated Diagnosis Cost |
|---|---|
| Toyota | $80 – $100 |
| Honda | $75 – $95 |
| Ford | $90 – $120 |
| Chevrolet | $95 – $125 |
| BMW | $120 – $150 |
| Mercedes | $140 – $170 |
Once the issue causing the P0171 error code has been identified, the next step is to fix the problem.
This can involve replacing the faulty component, cleaning or replacing the fuel injectors, or repairing a vacuum leak.
If you are not comfortable performing the repair yourself, it is recommended that you take your vehicle to a professional mechanic or dealership. They will have the necessary tools and expertise to fix the issue and ensure that your vehicle is running properly.
What happens when you don’t fix P0171 error?
When you don’t fix the P0171 error code, it can lead to several problems with your vehicle’s performance and fuel economy. Since the error code indicates that the fuel mixture in the engine is too lean, your engine is not getting enough fuel to operate efficiently.
This can cause the engine to run hot and put a strain on the engine components.
If the issue is not addressed, it can lead to more serious problems, such as engine damage, reduced power and acceleration, decreased fuel efficiency, and increased emissions. The catalytic converter may also be damaged due to increased exhaust gas temperatures, which can be expensive to replace.
Additionally, if the problem is not fixed, the check engine light will remain on, indicating that there is an issue with the vehicle’s emissions system. This may cause your vehicle to fail an emissions test, resulting in fines and penalties.