Engine-Codes - Gmc - P0172 GMC

P0172 GMC - Fuel Trim System Rich Bank 1

Repair Importance Level: 3/3
Repair Difficulty Level: 3/3  What is this?
Table of contents

P0172 GMC Possible Causes

  • Faulty Front Heated Oxygen Sensor
  • Faulty Spark Plugs
  • Faulty Mass Air Flow (MAF) sensor
  • Exhaust Gas Leaks
  • Ignition Misfiring
  • Incorrect Fuel Pressure
  • Faulty Fuel Injectors

How is the P0172 GMC code repair?

Start by checking the "Possible Causes" listed above. Visually inspect the related wiring harness and connectors. Check for damaged components and look for broken, bent, pushed out, or corroded connector's pins.

Tech Notes

There is a Factory Service Bulletin for all 2000-2013 GMC models:
2000-2013 GMC Factory Service Bulletin OBDII Code P0172





User Submitted Video

What is the cost to diagnose the P0172 GMC code

Labor: 1.0

The cost to diagnose the P0172 GMC code is 1.0 hour of labor. The auto repair's diagnosis time and labor rates vary by location, vehicle's make and model, and even your engine type. Most auto repair shops charge between $75 and $150 per hour.
How much do you know about cars?

Take the AutoCodes.com automotive tests and turbo-charge your car repair knowledge

Play Now

When is the code detected?

- Fuel injection system does not operate properly.
- The amount of mixture ratio compensation is too large. (The mixture ratio is too rich.)

Possible Symptoms

  • Engine Light ON (or Service Engine Soon Warning Light)
  • Excessive Fuel Consumption

P0172 GMC Meaning

The Engine Control Module (ECM) controls the air/fuel metering system in order to provide the best possible combination of driveability, fuel economy, and emission control. Fuel delivery is controlled differently during Open Loop and Closed Loop. During Open Loop, the ECM determines fuel delivery based on sensor signals without heated oxygen sensor (HO2S) input. During Closed Loop, the ECM adds HO2S inputs to calculate the short and long term fuel trim (FT) adjustments. If the HO2S indicates a lean condition, the fuel trim values will be above 0 percent. If the HO2S indicates a rich condition, the FT values will be below 0 percent. The short term FT values change rapidly in response to the HO2S voltage signals. The long term FT makes coarse adjustments in order to maintain an air/fuel ratio of 14.7:1.

More Information

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

Need more help?

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