P0173 Fuel system trim fault (bank 2)

P0173 – OBD-II Trouble Code Technical Description

Trouble code P0173 indicates a fuel mixture imbalance (bank 2).

What does the fault code mean P0173?

Trouble code P0173 indicates that the fuel mixture level in bank 2 is too high. This means that the fuel mixture control system has detected that there is more fuel in the mixture than expected. This can be due to various problems in the fuel injection system, air system or oxygen sensor.

Possible reasons

Some possible causes of the P0173 trouble code:

• Oxygen sensor (O2): The oxygen sensor measures the oxygen content of the exhaust gases and helps the engine management system adjust the fuel-air mixture. If the oxygen sensor fails or is faulty, it may produce incorrect signals, causing the mixture to be too rich.
• Mass Air Flow (MAF) Sensor: The mass air flow sensor measures the amount of air entering the engine and helps the engine management system regulate the fuel/air mixture. If the MAF sensor is faulty or dirty, it may send incorrect data, causing the mixture to be too rich.
• Problems with fuel injectors: Clogged or faulty fuel injectors can cause fuel to not atomize properly, resulting in a mixture that is too rich.
• Fuel pressure problems: Low fuel pressure or problems with the fuel pressure regulator can lead to improper fuel delivery to the engine, which can also cause the mixture to be too rich.
• Problems with the intake system: Intake manifold leaks, improperly installed sensors, or air filter problems can also cause the mixture to be too rich.
• Problems with temperature sensors: Faulty engine temperature sensors can provide incorrect data to the engine management system, resulting in incorrect mixture calculations.
• Problems with the electrical system: Faulty wiring, corroded connectors, or other electrical problems can cause problems in the transmission of data between the sensors and the engine management system.

When a P0173 code appears, a thorough diagnosis must be performed to determine the specific cause of the problem.

What are the symptoms of a fault code? P0173?

Symptoms for trouble code P0173 indicating the engine's fuel/air mixture is too rich:

• Increased fuel consumption: Because a mixture that is too rich requires more fuel to burn, it may result in increased fuel consumption.
• Unsteady or rough idle: A mixture that is too rich can cause the engine to idle rough or rough, especially during cold starts.
• Poor engine performance: This may manifest itself as lack of power, poor throttle response, or overall poor engine performance.
• Black smoke from the exhaust pipe: Due to excess fuel in the mixture, combustion may produce black smoke from the exhaust pipe.
• Smell of fuel in exhaust gases: Excessive fuel may cause fuel odor in the exhaust.
• Check Engine Light Appears: Code P0173 activates the Check Engine Light on your vehicle's dashboard, indicating that there is a problem with the fuel/air mixture system.

How to diagnose a fault code P0173?

To diagnose DTC P0173, the following procedure is recommended:

1. Scan error code: Use a diagnostic scanner to determine the P0173 code and any other codes that may be stored in the system.
2. Oxygen sensor test: Check the operation of the oxygen sensor in both bank 2 and bank 1. Evaluate their values ​​and make sure they are operating within normal limits.
3. Checking the Mass Air Flow (MAF) Sensor: Check the operation of the Mass Air Flow (MAF) sensor to ensure that it is providing the correct amount of air entering the engine.
4. Checking fuel injectors: Check the fuel injectors for leaks or blockages and make sure they are operating properly.
5. Fuel pressure check: Check the fuel injection pressure to make sure it is within the normal range.
6. Checking the intake system: Inspect the intake system for air leaks or other damage that may be causing the mixture to be too rich.
7. Checking temperature sensors: Check the engine temperature sensors to ensure they are reporting correct data.
8. Checking electrical connections: Inspect electrical connections and wires associated with sensors and other engine management system components for damage or corrosion.
9. Compression pressure testing: Check the compression pressure in the cylinders, as low compression pressure can also cause the mixture to be too rich.
10. Professional diagnostics: For complex problems or if you are unsure of your skills, it is recommended to contact a professional auto mechanic for more detailed diagnosis and repair.

Diagnostic errors

When diagnosing DTC P0173, the following errors may occur:

• Incorrect interpretation of oxygen sensor data: Incorrect interpretation of data from the oxygen sensor may lead to incorrect diagnosis. For example, incorrect exhaust gas oxygen readings may be caused by a faulty sensor or other factors such as a leaking intake system or malfunctioning fuel injectors.
• Problems with the mass air flow (MAF) sensor: Incorrect operation or malfunction of the mass air flow sensor can lead to incorrect interpretation of the amount of air entering the engine, which in turn can lead to a too rich mixture of fuel and air.
• Problems with fuel injectors: Clogged or malfunctioning fuel injectors can also cause fuel and air to not mix properly, which can cause P0173.
• Problems with the intake system: Air leaks or other problems with the intake system can cause uneven mixing of fuel and air, which may be incorrectly interpreted as a too rich mixture.
• Misdiagnosis of other components: Some mechanics may focus on just one component, such as the oxygen sensor, without conducting a full diagnosis of the entire engine management system, which can lead to incorrect diagnosis and repairs.
• Ignoring other error codes: The presence of other error codes that may affect the operation of the fuel and air management system should also be considered when diagnosing the P0173 code. For example, problems with the engine temperature sensor or fuel pressure can cause signals to be misinterpreted and cause P0173.

How serious is the fault code? P0173?

Trouble code P0173 indicates a problem with the engine's fuel/air mixture, which can cause improper operation and poor fuel economy. Although this may not pose an immediate risk to driving safety, it may result in increased emissions and reduced engine performance. Therefore, although this code is not security critical, it is recommended that you contact a professional as soon as possible to diagnose and resolve the problem. It is not recommended to ignore this error as it may lead to more serious engine problems in the future.

What repair will help eliminate the code? P0173?

Resolving the P0173 trouble code may require several steps depending on the specific cause of the problem, some possible repair actions include:

1. Checking for air leaks: Check the entire intake system for leaks. This may include checking connections, seals, and other intake system components. If leaks are found, they should be repaired.
2. Replacing the oxygen sensor (O2): If the oxygen sensor is identified as the cause of the problem, it should be replaced. It is recommended to use original or high-quality analogues to ensure reliable operation.
3. Cleaning or replacing the air filter: Check the air filter for contamination. If the filter is clogged or dirty, it should be cleaned or replaced.
4. Cleaning or replacing the mass air flow (MAF) sensor: If the Mass Air Flow (MAF) sensor is faulty, it should be cleaned or replaced.
5. Checking and cleaning fuel injectors: Fuel injectors may be clogged or malfunctioning, which may cause fuel and air to not mix properly. Check and clean or replace injectors as necessary.
6. Diagnostics of other sensors and components: Check the operation of other sensors such as engine temperature sensor, fuel pressure sensor and others, as well as the condition of the ignition system. Use diagnostic tools to identify any other problems.
7. Firmware or software update: In some cases, the problem may be related to the PCM software. A software update or firmware update may help resolve the issue.

If you are unsure of your skills or do not have the necessary equipment, it is recommended that you contact a qualified mechanic or auto repair shop for diagnosis and repair.

How to Diagnose and Fix P0173 Engine Code - OBD II Trouble Code Explain

P0173 – Brand-specific information

Trouble code P0173 relates to the engine management system and can be found on various makes of cars, some of them are:

1. Ford: Unregulated fuel supply system, bank 2 - mixture too rich.
2. Chevrolet / GMC: Mixture on jar 2 is too rich.
3. Toyota: Air/fuel mixture correction system is too rich.
4. Honda/Acura: Non-regulated secondary air system, bank 2 - mixture too rich.
5. Nissan/Infiniti: Fuel control system - mixture too rich.
6. BMW: Air-fuel mixture correction system - mixture too rich.
7. Mercedes-Benz: Long-term adaptive limitation of air-fuel mixture correction.

Typically, the P0173 code indicates a problem with the fuel/air mixture, which can be caused by a variety of things, such as intake system leaks, oxygen sensor problems, a clogged air filter, or problems with the fuel injection system.