AutoCodes – Generic – P0172

P0172 Code - Fuel Trim System Rich Bank 1

Quick Answer

The Engine Control Module (ECM) controls a Closed Loop air/fuel metering system to provide the best possible combination of drivability, fuel economy, and emission control. Common causes include Dirty or Faulty Mass Air Flow (MAF) Sensor, Intake Air Leaks, Exhaust Gas Leaks. 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: P0172 indicates Fuel Trim System Rich Bank 1.
Common causes: Common causes include Dirty or Faulty Mass Air Flow (MAF) Sensor, Intake Air Leaks, Exhaust Gas Leaks.
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.

Save to My Repairs Step-by-Step Diagnostic Guide My Repairs

AI answers can be wrong. Verify repairs with testing. Open full chat

Code Popularity 109,511

How popular is this code, among other codes? Medium

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 May 29, 2022

Description
Step-by-Step Diagnostic Guide
Possible Causes
How To Fix
Tech Notes ▶
Cost to Diagnose
Comments
Add Comment

💬 Need more help? Ask Coddy for instant answers — it's free!

Code P0172 Description

The Engine Control Module (ECM) controls a Closed Loop air/fuel metering system to provide the best possible combination of drivability, fuel economy, and emission control. The ECM monitors the Heated Oxygen Sensor (HO2S) signal voltage and adjusts the fuel delivery based on the signal voltage while in Closed Loop. A change made to the fuel delivery changes the long and short-term fuel trim values. The short-term fuel trim values change rapidly in response to the HO2S signal voltages. These changes fine-tune the engine fueling. The long-term fuel trim values change in response to trends in the short-term fuel trim. The long-term fuel trim makes coarse adjustments to fueling to re-center and restore control to short-term fuel trim. The ideal fuel trim values are around 0 %. A positive fuel trim value indicates that the ECM is adding fuel to compensate for a lean condition. A negative fuel trim value indicates that the ECM is reducing the amount of fuel to compensate for a rich condition. The Diagnostic Trouble Code (DTC) will be set when the average long-term fuel trim weighted average value is greater or less than a calibrated value.

OBDII Code P0172 - Fuel Trim System Rich Bank 1 - AutoCodes.com — P0172 Code - Fuel Trim System Rich Bank 1

What does this mean?

What are the Possible Causes of the DTC P0172?

Dirty or Faulty Mass Air Flow (MAF) Sensor
Intake Air Leaks
Exhaust Gas Leaks
Fuel Contamination
Faulty or Leaking Fuel Injectors
Faulty Front Heated Oxygen Sensor
Ignition Misfiring
Incorrect Fuel Pressure
Positive Crankcase Ventilation (PCV) Hose Leaks

How to Fix the DTC P0172?

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

The P0172 code means that more gasoline is detected in the exhaust gases exiting the combustion chamber. If the P0172 is set in along with the P0175 code, it is highly likely that the problem is caused by leaking fuel injectors. If there are no leaking fuel injectors, the next step is to replace the air filter and clean the Mass Air Flow (MAF) Sensor. If the problem persists the MAF or Front Heated Oxygen (O2) Sensor will need to be replaced.

Click Here to Learn What is Bank 1 and Bank 2

User Submitted Video

What is the Cost to Diagnose the Code?

Labor: 1.0

To diagnose the P0172 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.

Need more information about the P0172 code?

Need more information on how to fix the P0172 code? Get Access to Factory Service Manuals

Need Help with the Code?

Get the P0172 code diagnosed by a professional: Find a repair shop in your area

Information for Specific Makes

P0172 Acura — Fuel System Too Rich Bank 1
P0172 Audi — System Too Rich Bank 1
P0172 BMW — Mixture Control System Too Rich Bank 1
P0172 Buick — Fuel Trim System Rich Bank 1
P0172 Cadillac — Fuel Trim System Rich Bank 1
P0172 Chevrolet — Fuel Trim System Rich Bank 1
P0172 Chrysler — Fuel System 1/1 Lean Fuel System Rich
P0172 Dodge — Fuel System 1/1 Lean Fuel System Rich
P0172 Ford — System Too Rich Bank 1
P0172 GMC — Fuel Trim System Rich Bank 1
P0172 Honda — Fuel System Too Rich Bank 1
P0172 Hummer — Fuel Trim System Rich Bank 1
P0172 Hyundai — System Too Rich Bank 1
P0172 Infiniti — Fuel Injection System Too Rich Bank 1
P0172 Isuzu — Fuel Trim System Rich Bank 1
P0172 Jaguar — System Too Rich Bank 1
P0172 Jeep — Fuel System 1/1 Lean Fuel System Rich
P0172 KIA — Bank 1 System Too Rich
P0172 Lexus — Fuel Trim System Too Rich Bank 1
P0172 Mazda — Rich Air/Fuel Ratio Bank 1
P0172 Mercedes-Benz — System Too Rich Bank 1
P0172 MINI — Mixture Control System Too Rich Bank 1
P0172 Mitsubishi — System Too Rich- Cylinders 1-4
P0172 Nissan — Fuel Injection System Too Rich Bank 1
P0172 Oldsmobile — Fuel Trim System Rich Bank 1
P0172 Pontiac — Fuel Trim System Rich Bank 1
P0172 Saab — System Too Rich Bank 1
P0172 Saturn — Fuel Trim System Rich Bank 1
P0172 Scion — Fuel Trim System Too Rich Bank 1
P0172 Subaru — System Too Rich Bank 1
P0172 Toyota — Fuel Trim System Too Rich Bank 1
P0172 Volkswagen — System Too Rich Bank 1

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.