P0171 Scion Code - Fuel Trim System Too Lean Bank 1
Quick Answer
The fuel trim is related to the feedback compensation value, not to the basic injection duration. Common causes include Intake air leaks, Fuel injector blockage, Faulty Mass Air Flow (MAF) sensor. 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 Scion indicates Fuel Trim System Too Lean Bank 1.
- Common causes
- Common causes include Intake air leaks, Fuel injector blockage, Faulty Mass Air Flow (MAF) sensor.
- 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 Scion Description
The short-term fuel trim is fuel compensation that is used to constantly maintain the air-fuel ratio at stoichiometric levels. The signal from the air-fuel ratio sensor indicates whether the air-fuel ratio is rich or lean compared to the stoichiometric ratio. This triggers a reduction in the fuel injection volume if the air-fuel ratio is rich and an increase in the fuel injection volume if lean.
Factors such as individual engine differences, wear over time, and changes in the operating environment cause short-term fuel trim to vary from the central value. The long-term fuel trim, which controls overall fuel compensation, compensates for long-term deviations in the fuel trim from the central value caused by the short-term fuel trim compensation.
Under closed-loop fuel control, fuel injection volumes that deviate from those estimated by the Engine Control Module (ECM) cause changes in the long-term fuel trim compensation value. The long-term fuel trim is adjusted when there are persistent deviations in the short-term fuel trim values. Deviations from the fuel injection volumes estimated by the ECM also affect the average fuel trim learned value, which is a combination of the average short-term fuel trim (fuel feedback compensation value) and the average long-term fuel trim (learned value of the air fuel ratio). If the average fuel trim learned value exceeds the malfunction thresholds, the ECM interprets this as a fault in the fuel system and stores a Diagnostic Trouble Code (DTC).
What are the Possible Causes of the DTC P0171 Scion?
- Intake air leaks
- Fuel injector blockage
- Faulty Mass Air Flow (MAF) sensor
- Faulty Engine Coolant Temperature Sensor
- Faulty Air Fuel Ratio (A/F) Sensor (Front Oxygen Sensor)
- Incorrect fuel pressure
- Gas leak from exhaust system
- Faulty Positive Crankcase Ventilation (PCV) hose connection
- Air Fuel Ratio Sensor harness is open or shorted
- Air Fuel Ratio Sensor circuit poor electrical connection
- Faulty Engine Control Module (ECM)
How to Fix the DTC P0171 Scion?
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
What is the Cost to Diagnose the Code?
Labor: 1.0
To diagnose the P0171 Scion 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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Information for Specific Scion Models
- P0171 2005 Scion xB — Air/Fuel Mixture System Lean Bank 1
- P0171 2006 Scion xB — Air/Fuel Mixture System Lean Bank 1
- P0171 2007 Scion xB — Air/Fuel Mixture System Lean Bank 1
Frequently Asked Questions about P0171 Scion Code
1. What are the common symptoms of OBDII code P0171 in a Scion?
- Common symptoms of code P0171 in a Scion include rough idling, poor fuel economy, hesitation or stalling during acceleration, and the illumination of the Check Engine Light.
2. What does the OBDII code P0171, indicating "Fuel Trim System Too Lean Bank 1," mean for a Scion?
- Code P0171 in a Scion signifies that the engine control module has detected a lean air-fuel mixture on bank 1 of the engine. This can lead to inefficient combustion and potential engine performance issues.
3. What are some possible causes of code P0171 in a Scion?
- Common causes of code P0171 in a Scion include a vacuum leak, faulty oxygen sensor, dirty or clogged fuel injectors, a malfunctioning mass airflow sensor, or a weak fuel pump.
4. How can I diagnose the cause of OBDII code P0171 in my Scion?
- To diagnose code P0171 in a Scion, you can start by inspecting for any visible vacuum leaks, checking the oxygen sensor and mass airflow sensor readings, testing the fuel pressure, and inspecting the fuel injectors for blockages.
5. Is it safe to continue driving my Scion with OBDII code P0171 present?
- While you may still be able to drive your Scion with code P0171, it is not recommended as it can lead to poor engine performance, reduced fuel efficiency, and potentially cause damage to the catalytic converter over time.
6. How can I repair OBDII code P0171 in my Scion?
- Repairing code P0171 in a Scion typically involves fixing the root cause of the lean condition, such as replacing a faulty oxygen sensor, repairing vacuum leaks, cleaning or replacing fuel injectors, or addressing issues with the mass airflow sensor.
7. Can a dirty air filter trigger OBDII code P0171 in a Scion?
- Yes, a dirty air filter can restrict the airflow into the engine, causing a lean condition and potentially triggering code P0171 in a Scion. It is recommended to check and replace the air filter if necessary.
8. Will resetting the Check Engine Light resolve OBDII code P0171 in a Scion?
- Simply resetting the Check Engine Light will not fix the underlying issue causing code P0171 in a Scion. It is essential to diagnose the problem, make necessary repairs, and clear the code using a diagnostic scanner.
9. Are there any maintenance tips to prevent OBDII code P0171 in a Scion?
- To help prevent code P0171 in a Scion, perform regular maintenance such as changing the fuel filter as recommended, keeping the air filter clean, using high-quality fuel, and addressing any engine performance issues promptly.
10. Can a faulty fuel pressure regulator cause OBDII code P0171 in a Scion?
- Yes, a faulty fuel pressure regulator can disrupt the proper fuel delivery to the engine, leading to a lean air-fuel mixture and triggering code P0171 in a Scion. It is advisable to have the fuel pressure regulator inspected and replaced if necessary.
Discuss the causes and fixes for P0171 Scion OBDII Code
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I have a 2010 Scion xB and cannot for the life of me get rid of the P1071 code system bank too lean code. I have replaced the mass air flow sensor (Walker brand name) replaces the gaskets, metal one in the front and under the head as well as the intake manifold gasket. I have also replaced the throttle body. The code will not go away. Just ordered new injectors (Denso Brand) re ordered the Denso MAF Sensor to see if replacing the sensor is the issue. Need major help!!!
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Have you replace the Oxygen Sensor? For you model year the Oxygen Sensor is one of the most common problems that will set the P0171 code.
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I have never had that problem before, usually the Oxygen Sensor or MAF will take care of the problem.
Here is a list of the most common solutions, according to a national database of repairs for you model and year. I hope that helps- Oxygen Sensor - 68 times
- Mass Airflow Sensor - 56
- Fuel Pump - 26
- Spark Plug - 14
- EVAP Purge Solenoid Valve - 10
- Positive Crankcase Ventilation Hose - 6 -
Got a ??? Codes saying lean bank large leak and every time I put gas it does not start on the first turn over anybody who can help out thanks
Code p1071 someone said replace the fuel pump is that the only thing it can be ????? -
There are many things that could set the P0171 code, the fuel pump is not the most common problem. Let me check if I can find more information, what model and year is your Scion?
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