AutoCodes – BMW – P0173 BMW

P0173 BMW Code - Fuel Trim Malfunction Bank 2

Quick Answer

With the Air/Fuel Mixture Ratio Self-Learning Control, the actual mixture ratio can be brought closely to the theoretical mixture ratio based on the mixture ratio feedback signal from the heated oxygen sensors 1. Common causes include Intake air leaks, Faulty front heated oxygen sensor, Ignition misfiring. Severity is High - diagnose this code as soon as possible. Driving is not recommended if the warning light is flashing, the engine runs poorly, or safety-related symptoms are present.

What it means: P0173 BMW indicates Fuel Trim Malfunction Bank 2.
Common causes: Common causes include Intake air leaks, Faulty front heated oxygen sensor, Ignition misfiring.
Severity: High - diagnose this code as soon as possible.
Can I drive?: Driving is not recommended if the warning light is flashing, the engine runs poorly, or safety-related symptoms are present.

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Code Popularity 20,524

How popular is this code, among other codes? Low

Repair Importance Level

Urgent (Diagnose now) (3 / 3)

Repair Difficulty Level

Advanced (Pro) (3 / 3)

What is this?

Table of contents Created and updated by William Orellana on Aug 14, 2020

Description
Possible Causes
How To Fix
Tech Notes ▶
Cost to Diagnose
FAQs
Comments
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Code P0173 BMW Description

With the Air/Fuel Mixture Ratio Self-Learning Control, the actual mixture ratio can be brought closely to the theoretical mixture ratio based on the mixture ratio feedback signal from the heated oxygen sensors 1. The Engine Control Module (ECM) calculates the necessary compensation to correct the offset between the actual and the theoretical ratios.
In case the amount of the compensation value is extremely large (The actual mixture ratio is too lean.), the ECM judges the condition as the fuel injection system malfunction and light up the MIL (2 trip detection logic).

OBDII Code P0173 BMW - Fuel Trim Malfunction Bank 2 - AutoCodes.com — P0173 BMW Code - Fuel Trim Malfunction Bank 2

What does this mean?

What are the Possible Causes of the DTC P0173 BMW?

Intake air leaks
Faulty front heated oxygen sensor
Ignition misfiring
Faulty fuel injectors
Exhaust gas leaks
Incorrect fuel pressure
Lack of fuel
Faulty Mass Air Flow (MAF) sensor
Incorrect Positive Crankcase Ventilation (PCV) hose connection

How to Fix the DTC P0173 BMW?

Review the 'Possible Causes' above and visually examine the corresponding wiring harness and connectors. Check for damaged components and inspect connector pins for signs of being broken, bent, pushed out, or corroded.

What does this mean?

Code Tech Notes

Dirty air filter of faulty air flow sensor are common causes for the P0173 code of the problem.

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What is the Cost to Diagnose the Code?

Labor: 1.0

To diagnose the P0173 BMW code, it typically requires 1.0 hour of labor. Rates vary by location, vehicle, and shop. Many shops charge between $80–$150 per hour; dealerships and metro areas may be higher, independents may be lower.

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About the author: William Orellana is a Master Mechanic and Mechanical Engineer with over 30 years of experience diagnosing and repairing vehicles. Learn more about his background.

Frequently Asked Questions about P0173 BMW Code

1. What are the common symptoms of OBDII code P0173 (Fuel Trim Malfunction Bank 2) in a BMW?

- Common symptoms include rough idling, reduced fuel efficiency, engine hesitation, and potentially a check engine light.

2. What are the possible causes of OBDII code P0173 in a BMW?

- Causes may include a faulty oxygen sensor, vacuum leaks, a dirty or faulty mass airflow sensor, a malfunctioning fuel injector, or a problem with the fuel pressure regulator.

3. How can I diagnose the issue causing OBDII code P0173 in my BMW?

- Diagnose the issue by checking for vacuum leaks, inspecting the oxygen sensor, testing the mass airflow sensor, and ensuring proper fuel pressure and injector function.

4. Can a dirty air filter trigger OBDII code P0173 in a BMW?

- Yes, a dirty air filter can disrupt the air-fuel mixture and lead to a fuel trim malfunction, potentially triggering code P0173.

5. Is it safe to continue driving my BMW with OBDII code P0173 present?

- It is generally not recommended to drive extensively with code P0173 as it can lead to further engine issues and reduced performance.

6. How can I reset OBDII code P0173 in my BMW?

- Resetting the code can be done using an OBDII scanner or by disconnecting the car's battery for a few minutes, but the underlying issue should still be addressed to prevent the code from reappearing.

7. Can a faulty catalytic converter cause OBDII code P0173 in a BMW?

- A faulty catalytic converter could potentially cause code P0173 if it is affecting the proper air-fuel mixture, but it is not among the most common causes.

8. Are there any DIY repair tips for addressing OBDII code P0173 in a BMW?

- DIY tips include checking for visible vacuum leaks, cleaning the mass airflow sensor, ensuring the air filter is clean, and inspecting the oxygen sensor for any issues.

9. How much does it cost to repair OBDII code P0173 in a BMW?

- The cost of repairs can vary depending on the exact cause of the code, but it may range from $100 for a simple fix like cleaning a sensor to several hundred dollars for more complex issues.

10. Can a professional mechanic help diagnose and repair OBDII code P0173 in my BMW?

- Yes, a professional mechanic with experience in BMW vehicles can efficiently diagnose and repair the underlying issue causing code P0173 to ensure proper vehicle performance and reliability.