P0171 GMC Code - Fuel Trim System Lean 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 Restricted Air Filter, Dirty or Faulty Mass Air Flow (MAF) Sensor, Intake Air 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
- P0171 GMC indicates Fuel Trim System Lean Bank 1.
- Common causes
- Common causes include Dirty or Restricted Air Filter, Dirty or Faulty Mass Air Flow (MAF) Sensor, Intake Air 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.
Code P0171 GMC Description
What are the Possible Causes of the DTC P0171 GMC?
- Dirty or Restricted Air Filter
- Dirty or Faulty Mass Air Flow (MAF) Sensor
- Intake Air Leaks
- Exhaust Gas Leaks
- Fuel Contamination
- Faulty or Clogged Fuel Injectors
- Faulty Front Heated Oxygen Sensor
- Ignition Misfiring
- Low Fuel Pressure
- Positive Crankcase Ventilation (PCV) Hose Leaks
- Engine Control Temperature (ECT) inaccurate readings
How to Fix the DTC P0171 GMC?
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.
Code Tech Notes
Click Here to Learn What is Bank 1 and Bank 2
There are Factory Service Bulletins for the following GMC models:
2000-2013 GMC All Models:
2000-2013 GMC Factory Service Bulletin OBDII Code P0171
2005-2006 GMC Envoy Models
2007 GMC Yukon, Yukon Denali, Yukon XL Denali, Yukon XL with 5.3L or 6.0L Vortec V8 Engine
GMC Factory Service Bulletin OBDII Code P0171
2006 Trailblazer P0171
User Submitted Video
What is the Cost to Diagnose the Code?
Labor: 1.0
To diagnose the P0171 GMC 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 P0171 GMC code?
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Need Help with the Code?
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Information for Specific GMC Models
- P0171 2014 GMC Sierra — Fuel Trim System Lean Bank 1
- P0171 2015 GMC Sierra — Fuel Trim System Lean Bank 1
- P0171 2016 GMC Sierra — Fuel Trim System Lean Bank 1
- P0171 2017 GMC Sierra — Fuel Trim System Lean Bank 1
- P0171 2018 GMC Sierra — Fuel Trim System Lean Bank 1
Frequently Asked Questions about P0171 GMC Code
1. What does OBDII code P0171 GMC indicate?
- OBDII code P0171 for GMC vehicles signifies a "Fuel Trim System Lean Bank 1" condition, indicating that the engine is running too lean due to a lack of fuel in the air-fuel mixture.
2. What are common symptoms of OBDII code P0171 GMC?
- Common symptoms of code P0171 include rough idling, hesitation or stumbling during acceleration, poor fuel economy, and in some cases, a noticeable lack of power.
3. What are the possible causes of OBDII code P0171 GMC?
- Potential causes of code P0171 include a vacuum leak, faulty oxygen sensor, clogged fuel filter, malfunctioning mass airflow sensor, fuel pump issues, or a problem with the fuel injectors.
4. How can I diagnose the OBDII code P0171 GMC?
- To diagnose code P0171, you can start by checking for vacuum leaks, inspecting the air intake system for any faults, testing the oxygen sensor, scanning the mass airflow sensor, and ensuring the fuel delivery system is functioning properly.
5. Can a dirty air filter trigger the OBDII code P0171 GMC?
- Yes, a dirty air filter can restrict airflow into the engine, causing a lean fuel mixture and potentially triggering code P0171. It is recommended to inspect and replace the air filter if necessary.
6. How can I repair OBDII code P0171 GMC?
- Repairing code P0171 typically involves addressing the root cause, such as fixing vacuum leaks, replacing faulty sensors or filters, cleaning or replacing fuel injectors, and ensuring proper fuel pressure and delivery.
7. Is it safe to continue driving with OBDII code P0171 GMC?
- While the vehicle may still be operable with code P0171, it is not recommended to ignore the issue, as running too lean can lead to engine damage over time. It is advisable to address the problem promptly.
8. Can a bad fuel pump cause OBDII code P0171 GMC?
- Yes, a failing fuel pump can disrupt proper fuel delivery to the engine, resulting in a lean air-fuel mixture and triggering code P0171. It is important to have the fuel pump inspected and replaced if needed.
9. Will resetting the OBDII code P0171 GMC turn off the check engine light?
- Resetting the code may temporarily turn off the check engine light, but if the underlying issue causing code P0171 is not fixed, the light is likely to come back on once the problem is detected again.
10. How can I prevent OBDII code P0171 GMC from recurring?
- To prevent code P0171 from recurring, it is important to perform regular maintenance on your vehicle, including replacing air filters, checking for vacuum leaks, keeping the fuel system clean, and addressing any warning signs promptly.
Discuss the causes and fixes for P0171 GMC OBDII Code
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Here we go, 2002 Monte Carlo SS V6 3.8 engine light on. Initially problem started by vehicle just loosing power and wouldn't re-start until after a few moments ran awful got a few feet and then die again. I might add there was a strong odor of a very foul smell, but that went away eventually, any ideas, I have replaced MAF,OXY SENSOR UPPER BANK, GAS CAP, FUEL FILTER, AIR FILTER AND I might add I had a certified repair shop replace the MAF. His very expensive diagnostic equipment came up with the same code as I, P0171, which pretty well covers every above with exception of catalytic converter and air leaks. Othan that any ideas?
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The P0171 means that there is either not enough gas or too much air. Stuck fuel injectors or leaking intake gasket are common problems that can trigger this code.
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Thank you, but I do knew what the P0171 code read out meant, believe me I've done my homework on this one.
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I have a GMC envoy 2003 and it's not accelerating like it supposed to what can it be in replace the 02 sensor and put new air filter clean throttle also.can someone help [email protected]
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Unfortunately there are many things than can cause the P0171 code. Are there any more codes? any other symptoms?
The first you need to do is to check for intake leaks, if no leaks are found, you could try using high octane gas for a couple of weeks. Sometimes carbon built up could cause the code and high octane gas help clear the carbon.
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Thank you ok I check for leaks and nothing what I'm trying tomorrow is cleaning the injectors to see. I try to accelerate and down not want to pass 4300 and driving it's like an old car feeling
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I have a p0171 code and the inside of my car a very strong gas smell inside???? I’ve took it to two mechanics. It’s still not fixed? any suggestions? I’m a woman and don’t know what to do
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What model and year is your vehicle? I suggest taking your vehicle to an exhaust shop. The P0171 is not the cause of the problem, the P0171 code will be set when the car computer detects a lean mixture in the engine. Unfortunately, there are many things that can set the code, but an exhaust leak near the oxygen sensor can give you the gas smell and set the code. Also, you have to check for fuel leak around the fuel injectors.
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