P0171 is the error code displayed, along with the “Check Engine” light being on. Why does this matter? Most folks think it’s a problem with the oxygen sensors.
In actuality, it doesn’t indicate that the oxygen sensor is faulty. But what is it exactly? You can get a breakdown of it in this article.
The P0171 fault code indicates the car’s engine system’s improper air-to-fuel ratio.
What does P0171, a failure code, mean?
The car’s powertrain control module (PCM) continuously monitors the fuel delivery system’s adaptive fuel strategy to ensure the engine operates at the recommended air-to-fuel ratio of 14.7:1.
To help control the amount of gasoline being given to the engine, the computer (or computers) automatically modifies the injector pulse.
The computer receives the data from the oxygen sensor and utilizes it to calculate how much gasoline is required.
The computer will then adjust the fuel flow (and maybe other system-related operational characteristics) to maintain the proper air-to-fuel ratio.
The engine continues to run while this loop continues. When the computer has exceeded the rich calibration limit and can no longer hold the correct air/fuel ratio, fault code P0171 is shown.
Typical Signs of Fault Code P0171
The following are the most typical symptoms:
- On the Check Engine light
- Absence of electricity
- Roughness when the engine is idle due to spark knock
- Excess weight when accelerating
- High fuel use and overloading
P0171 problem code causes that could occur
These factors all contribute to the occurrence of this error:
- The issue with the mass air flow sensor.
- Upstream of the mass air flow sensor, vacuum leaks occur.
- The PCV line or vacuum connector may have cracks or damage.
- Defective or clogged PCV line
- Faulty or defective oxygen sensor
- Fuel injector malfunction
- A dirty filter brings on low fuel pressure.
- First engine leak and oxygen sensor
How grave is the P0171 error code?
Although parts and components are unlikely to be damaged in most P0171 code instances, they should be taken extremely seriously.
When this code is present in automatic gearbox systems, for example, the PCM/TCM might not always be able to efficiently control the shift pattern if the engine is hesitant and revving up, as is frequently the case with many BMW models.
How can the P0171 error be checked?
Use your OBD II scanner to find the problem code when the “Engine Light” is on. If the scanner displays P0171, a fault code related to a lean engine has appeared in the system.
This trouble code is set off when the computer detects the maximum enrichment settings.
How can this issue be solved?
You will require some items to solve this issue. The following are the items you will need:
- Code reader Flashlight Gloves and goggles for protection
- Wrench socket set
- Wrench
- Start by parking the car on flat ground and applying the emergency brakes.
1. Look for vacuum leaks
An error code relating to lead mixing can be brought on by unmetered air entering the engine intake system.
As a result, look for vacuum line breaks or degradation. Naturally, it would be best if you also inspected the caliber of the vacuum hoses at each end.
Gaskets are used in the intake system to seal their parts. Vacuum leaks from damaged gaskets can produce a code failure.
Lightly misting a carburetor cleaner around the gasket surface makes it possible to detect any potential leaks. An increase in engine idle speed will be seen if a leak is present.
2. Test for exhaust leaks
The engine’s pressure and vacuum cycles are controlled by the exhaust system. The oxygen sensor will display a lean reading if there is an exhaust leak because fresh air will enter the engine through the exhaust vent’s negative pressure side.
Have someone start the engine and hold the idle at 1,500 rpm for you to check for vacuum leaks.
After that, try listening for any sounds from the system’s exhaust, especially the head pipes and manifold. Scott can also indicate an exhaust leak, so keep an eye out for that.
3. Test the mass air flow sensor
After many miles of driving, the hot wire (the mass air flow sensor’s filament) may become contaminated by air pollutants, producing erroneous readings.
If you remove these minute residues, the sensor will read correctly and clean the filament safely.
4. Examine the oxygen sensor
Check the oxygen sensor exhaust system’s functionality. If the sensor malfunctions, it will provide inaccurate data, frequently displaying a lean mixture code.
5. Examine the spark plug
When the engine misfires, the virtually clean oxygen charge is transferred to the exhaust system. The system will receive a “lean” readout from the O2 sensor. However, tuning is a simple answer to this.
6. Consider switching out the air intake boot
The MAF sensor sends air from the engine to the throttle through the air intake boot. The air mass sensor tool code will display a false reading if it fails.
To achieve proper functionality after making these modifications, drive the car at a speed of roughly 30 mph while clearing the error codes and allowing the computer monitors to reset.
