AutoCodes – Ford – P0173 Ford

P0173 Ford 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 Ford 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 1,939

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 Jun 12, 2021

Description
Possible Causes
How To Fix
Tech Notes
Cost to Diagnose
FAQs
Comments
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Code P0173 Ford 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 Ford - Fuel Trim Malfunction Bank 2 - AutoCodes.com — P0173 Ford Code - Fuel Trim Malfunction Bank 2

What does this mean?

What are the Possible Causes of the DTC P0173 Ford?

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 Ford?

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

A dirty air filter or a faulty air flow sensor is a common cause for the P0173 code of the problem.

What is the Cost to Diagnose the Code?

Labor: 1.0

To diagnose the P0173 Ford 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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Need Help with the Code?

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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 Ford Code

What does the OBDII code P0173 mean on a Ford vehicle?

1. P0173 indicates a "Fuel Trim Malfunction Bank 2," meaning the engine control module (ECM) is detecting an issue with the fuel mixture adjustments on the bank of cylinders opposite the number one cylinder. 2.

What are the common symptoms of a P0173 code in a Ford?

Symptoms may include poor fuel economy, rough idling, engine misfires, hesitation during acceleration, and the check engine light illuminating. 3.

What causes the P0173 code on a Ford?

Common causes include a faulty mass airflow (MAF) sensor, vacuum leaks, exhaust leaks before the oxygen sensor, clogged fuel injectors, a failing fuel pressure regulator, or defective oxygen sensors. 4.

How does a vacuum leak trigger the P0173 code on a Ford?

A vacuum leak allows unmetered air into the engine, causing the air-fuel mixture to become too lean, which the ECM struggles to correct, triggering the code. 5.

Can a dirty mass airflow (MAF) sensor cause the P0173 code?

Yes, a dirty or faulty MAF sensor can misread the airflow entering the engine, leading to incorrect fuel adjustments and triggering the code. 6.

Is it safe to drive a Ford with a P0173 code?

While it may be possible to drive with this code, it is not recommended as it can lead to reduced performance, increased emissions, and potential engine damage if left unaddressed. 7.

How can I diagnose the P0173 code on my Ford?

Start by checking for vacuum leaks, inspecting the MAF sensor, testing the oxygen sensors, and ensuring the fuel injectors and fuel pressure are functioning properly. Scanning live data with an OBDII tool can also help pinpoint the issue. 8.

What repairs can fix the P0173 code on a Ford?

Repairs may include cleaning or replacing the MAF sensor, fixing vacuum or exhaust leaks, replacing faulty oxygen sensors, cleaning fuel injectors, or repairing issues with the fuel pressure regulator. 9.

How much does it cost to fix a P0173 code on a Ford?

Repair costs vary depending on the cause but can range from $50 for a sensor cleaning to several hundred dollars for parts like oxygen sensors or injectors. 10.

Can a clogged air filter cause a P0173 code on a Ford?

A severely clogged air filter can restrict airflow to the engine, potentially causing fuel trim issues, but it is less common compared to other causes like MAF sensor or vacuum leaks.