P0173 Fuel Trim Malfunction Bank 2: Diagnosis & Solutions

The P0173 trouble code signals a fuel trim malfunction on bank 2, indicating an improper air-fuel mixture in the engine’s second bank, affecting performance in vehicles like the P0173 Ford F-150 and P0173 Chevrolet Silverado. This guide covers causes, symptoms, and fixes, using the iCarsoft CR MAX BT

1. What Does P0173 Mean?

P0173 is an OBD-II diagnostic trouble code (DTC) defined as “Fuel Trim Malfunction (Bank 2).” The Engine Control Module (ECM) detects that the air-fuel mixture on the engine’s second bank (cylinders controlled by the second oxygen sensor) is too rich or too lean. Related codes include P0118 (coolant sensor high voltage), P0119 (intermittent coolant sensor), P0120 (throttle position sensor), and P0128 (coolant thermostat issue).

Role of Fuel Trim

Fuel trim adjusts the air-fuel ratio for optimal combustion (ideally 14.7:1). A P0173 fuel trim issue indicates the ECM cannot correct the mixture, leading to poor performance or emissions.

2. Causes of P0173 Fuel Trim Issue

Common causes of P0173 fuel trim issues include:

• Faulty Mass Air Flow (MAF) Sensor: Sends incorrect airflow data. Example: A 2017 Ford F-150 had a dirty MAF sensor, triggering P0173.
• Vacuum Leaks: Unmetered air enters the intake. Example: A 2018 Chevrolet Silverado had a cracked intake hose.
• Faulty Oxygen Sensor: Provides inaccurate exhaust data. Example: A 2016 Dodge Ram had a failing bank 2 O2 sensor.
• Clogged Fuel Injectors: Disrupts fuel delivery. Example: A 2019 Toyota Tundra showed P0173 due to dirty injectors.
• ECM Software Issue: Rare misinterpretation of sensor data.

3. Symptoms of P0173

Symptoms of a P0173 fuel trim issue include:

• Check Engine Light: Illuminates due to ECM detection.
• Rough Idle: Engine misfires or shakes at idle.
• Poor Acceleration: Reduced power during driving.
• Increased Fuel Consumption: Inefficient air-fuel mixture.
• Emissions Test Failure: Excess emissions from improper combustion.

Learn more about OBD-II codes at MotorTrend.

4. Vehicles Prone to P0173

P0173 is common in vehicles with V6 or V8 engines, where bank 2 is separate, including:

• P0173 Ford F-150 fix (2015-2020): Dirty MAF sensor, rough idle.
• P0173 Chevrolet Silverado repair (2014-2019): Vacuum leak, poor acceleration.
• Dodge Ram (2016-2020): Faulty O2 sensor, emissions issues.
• Toyota Tundra (2015-2019): Clogged injectors, fuel economy drop.
• GMC Sierra (2014-2018): Intake leaks, misfires.

5. How to Diagnose P0173

Diagnose P0173 fuel trim issues with the iCarsoft CR MAX BT :

1. Connect Scanner: Plug into the OBD-II port under the dashboard.
2. Read Codes: Retrieve P0173 and related codes (e.g., P0170).
3. Monitor Live Data: Check fuel trim values (short-term and long-term, ideally ±5%) and O2 sensor readings.
4. Inspect MAF Sensor: Clean or test for proper voltage. Example: F-150’s MAF was contaminated.
5. Check for Vacuum Leaks: Inspect hoses and gaskets. Example: Silverado’s intake hose was cracked.
6. Test O2 Sensor: Verify bank 2 sensor response with a multimeter.

6. How to Fix P0173

Fixes for P0173 fuel trim issues include:

• Clean/Replace MAF Sensor: Clean with MAF cleaner (~$10) or replace (~$50-$150). Example: F-150’s issue resolved after cleaning.
• Repair Vacuum Leaks: Replace hoses or gaskets (~$20-$100). Example: Silverado’s hose fixed.
• Replace O2 Sensor: Install new bank 2 sensor (~$50-$120). Example: Ram’s sensor replaced.
• Clean/Replace Fuel Injectors: Use cleaner (~$15) or replace (~$100-$300). Example: Tundra’s injectors cleaned.
• Update ECM: Reprogram if needed (~$0-$150).

7. Preventing P0173 Issues

• Clean MAF sensor every 30,000 miles.
• Inspect intake hoses and gaskets regularly.
• Replace O2 sensors per manufacturer schedule (100,000-150,000 miles).
• Use iCarsoft CR MAX BT for routine diagnostics.

8. User Case Studies

9. FAQs About P0173

Q: What causes a P0173 fuel trim issue?
A: Faulty MAF sensor, vacuum leaks, faulty O2 sensor, clogged injectors, or ECM errors.

Q: Is it safe to drive with P0173?
A: Driving risks poor performance and emissions failure. Diagnose with iCarsoft CR MAX BT.

Q: How does P0173 differ from P0170 or P0120?
A: P0173 is specific to bank 2 fuel trim, while P0170 is general fuel trim, and P0120 involves throttle position.

Q: Can P0173 cause engine damage?
A: Long-term, a lean or rich mixture may harm the engine.

Q: How long does it take to fix P0173?
A: Repairs take 1-3 hours (e.g., MAF cleaning vs. injector replacement).

Q: How much does it cost to fix P0173?
A: Costs range from $10 (MAF cleaner) to $300 (injectors).

Q: How often should I check my intake system?
A: Inspect MAF and hoses every 15,000 miles.

10. Summary

The P0173 fuel trim issue affects vehicles like the P0173 Ford F-150 and P0173 Chevrolet Silverado. Use the iCarsoft CR MAX BT  to diagnose and fix MAF, vacuum, or O2 sensor issues, ensuring optimal performance.