AutoCodes – Buick – P0171 2002 Buick LeSabre

P0171 2002 Buick LeSabre 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 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: P0171 2002 Buick LeSabre indicates Fuel Trim System Lean Bank 1.
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 9,916

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 Feb 06, 2023

Description
Step-by-Step Diagnostic Guide
Possible Causes
How To Fix
Tech Notes
Cost to Diagnose
FAQs
Comments
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Code P0171 2002 Buick LeSabre 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 P0171 2002 Buick LeSabre - Fuel Trim System Lean Bank 1 - AutoCodes.com — P0171 2002 Buick LeSabre Code - Fuel Trim System Lean Bank 1

What does this mean?

What are the Possible Causes of the DTC P0171 2002 Buick LeSabre?

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 P0171 2002 Buick LeSabre?

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

If the P0171 is combined with the P0174 code, it's very likely that the problem is caused by an intake leak. If there are no intake leaks, the next step is to replace the air filter and clean the air flow meter. If the problem persists the front oxygen (O2) sensor may need to be replaced.
The P0171 code could also be caused may be caused by one or more of the following: debris on the MAF sensor causing an incorrect reading, improper oil level, low or high fuel pressure, or Engine Control Temperature (ECT) Sensor reading inaccurate.

There is a Factory Service Bulletin for the 2002 Buick LeSabre:
2002 Buick LeSabre Factory Service Bulletin OBDII Code P0171

What is the Cost to Diagnose the Code?

Labor: 1.0

To diagnose the P0171 2002 Buick LeSabre 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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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 P0171 2002 Buick LeSabre Code

1. What does OBDII code P0171 on a 2002 Buick LeSabre mean?

The code P0171 indicates a "Fuel Trim System Lean Bank 1" error, which means the engine is running too lean on fuel.

2. What are common symptoms of OBDII code P0171 on a 2002 Buick LeSabre?

Common symptoms include rough idle, poor acceleration, stalling, hesitation, and possible fuel odor.

3. What are the common causes of OBDII code P0171 on a 2002 Buick LeSabre?

Common causes include a vacuum leak, faulty oxygen sensor, clogged fuel filter, dirty mass airflow sensor, or a malfunctioning fuel injector.

4. How can I diagnose the OBDII code P0171 on a 2002 Buick LeSabre?

Diagnosis involves checking for vacuum leaks, testing the oxygen sensor, inspecting the air intake system, examining the fuel injectors, and scanning for other possible issues using an OBDII scanner.

5. What are some repair tips for fixing OBDII code P0171 on a 2002 Buick LeSabre?

Repair tips include fixing any vacuum leaks, replacing the oxygen sensor if necessary, cleaning or replacing the mass airflow sensor, changing the fuel filter, and ensuring the fuel system is functioning properly.

6. Can driving with OBDII code P0171 on a 2002 Buick LeSabre cause further damage?

Continuing to drive with this code may lead to decreased fuel efficiency, engine misfires, and potential damage to the catalytic converter over time.

7. How much does it typically cost to repair OBDII code P0171 on a 2002 Buick LeSabre?

The cost of repairs can vary depending on the specific issue, but it may range from $100-$500 or more, including parts and labor.

8. Can I reset the OBDII code P0171 on a 2002 Buick LeSabre by disconnecting the battery?

While disconnecting the battery may clear the code temporarily, it is recommended to diagnose and fix the underlying issue to prevent the code from reoccurring.

9. Is it safe to drive my 2002 Buick LeSabre with OBDII code P0171?

It is not recommended to drive extensively with this code as it can lead to poor engine performance and potential long-term damage. It's best to address the issue promptly.

10. How often does OBDII code P0171 occur in 2002 Buick LeSabres?

Code P0171 is a relatively common issue in older vehicles like the 2002 Buick LeSabre, often caused by wear and tear on various engine components. Regular maintenance can help prevent this code from appearing.