Toyota AVALON The 6 Most Common OBD DTC

Toyota AVALON The 6 Most Common OBD DTC

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Toyota AVALON The 6 Most Common OBD DTC Problems

Toyota Avalon owners should know the most common OBD Diagnostic Trouble Codes (DTC) so they can figure out what might be wrong with their car and fix it. In this article, we list the  6 most common DTC codes for Toyota Avalon cars, which are P0500, P1604, P0171, C1201, C1301, and B150A. By getting to know these codes, you can find problems more quickly and keep your Avalon running well and reliably.

DTC Code: P0500 – Vehicle Speed Sensor “A” Malfunction

 

Description: The P0500 code indicates a malfunction in the vehicle speed sensor circuit “A.” This sensor measures the speed of the vehicle and sends that information to the Engine Control Module (ECM), Transmission Control Module (TCM), and other relevant systems.

Symptoms:

  • Speedometer not working or intermittent
  • Harsh or erratic shifting
  • Reduced fuel efficiency
  • Illuminated Check Engine Light (CEL) or Malfunction Indicator Lamp (MIL)
  • Traction Control System (TCS) or Anti-Lock Brake System (ABS) warning light
  • Poor acceleration
  • Cruise control not functioning

Cause:

  • Faulty vehicle speed sensor
  • Damaged or corroded wiring or connectors
  • Malfunctioning ECM or TCM
  • Faulty speedometer instrument cluster
  • Damaged wheel bearing or hub assembly

Possible Location:

  • Vehicle speed sensor (usually located on the transmission or near the wheel hub assembly)
  • Wiring harnesses connected to the vehicle speed sensor
  • ECM or TCM

How to Fix the Problem:

  1. Inspect the vehicle speed sensor and its wiring for damage, corrosion, or loose connections. Repair or replace as needed.
  2. Test the vehicle speed sensor with a multimeter to ensure it is functioning properly. Replace the sensor if faulty.
  3. Check the wheel bearing and hub assembly for damage or excessive play. Repair or replace as needed.
  4. Inspect and test the ECM, TCM, and speedometer instrument cluster. Repair or replace if necessary.

How Difficult to Fix: Moderate. DIYers with some automotive knowledge and experience can perform most of the diagnostic and repair steps. However, working with the ECM or TCM may require specialized equipment and expertise.

Can You Drive With This Code: It is not recommended to drive with this code, as it can lead to erratic shifting, poor acceleration, and reduced safety features such as TCS and ABS.

How to Clear the Code: After fixing the problem, clear the code with an OBD-II scanner. Disconnecting the battery may reset the code and the ECM’s learned data, but it is not the preferred method. It’s important to address the underlying issue and use a proper scan tool to reset the code.

Tools Needed to Use:

  1. OBD-II scanner – to read and clear the code
  2. Multimeter – to test the vehicle speed sensor and wiring
  3. Basic hand tools – for removing and installing components
  4. Specialized tools – for diagnosing and repairing ECM or TCM issues (if applicable)

 

DTC Code: P1604 – Startability Malfunction

 

Description: The P1604 code indicates that the Engine Control Module (ECM) has detected a startability problem, meaning the engine is unable to start or experiences difficulty starting. This code is specific to Toyota and Lexus vehicles, including the Avalon.

Symptoms:

  • Difficulty starting the engine
  • Engine cranking but not starting
  • Intermittent starting issues
  • Illuminated Check Engine Light (CEL) or Malfunction Indicator Lamp (MIL)

Cause:

  • Weak or dead battery
  • Faulty starter motor or solenoid
  • Poor electrical connections in the starting circuit
  • Malfunctioning ignition switch
  • Faulty fuel pump or fuel pump relay
  • Clogged fuel filter
  • Faulty ECM

Possible Location:

  • Battery
  • Starter motor and solenoid
  • Starting circuit wiring and connections
  • Ignition switch
  • Fuel pump and fuel pump relay
  • Fuel filter
  • ECM

How to Fix the Problem:

  1. Test the battery for proper voltage and health. Charge or replace the battery if necessary.
  2. Inspect the starter motor and solenoid for damage or wear. Test their operation and replace if necessary.
  3. Check the starting circuit wiring and connections for corrosion, damage, or loose connections. Repair or replace as needed.
  4. Test the ignition switch for proper operation. Replace if faulty.
  5. Check the fuel pump and fuel pump relay for proper operation. Replace if necessary.
  6. Inspect the fuel filter for clogs and replace if needed.
  7. Test the ECM for proper operation and replace if necessary.

How Difficult to Fix: Moderate. Some steps, such as testing and replacing the battery, can be performed by DIYers. However, diagnosing and repairing issues with the ECM or starter motor may require specialized tools and expertise.

Can You Drive With This Code: Driving with this code is not recommended, as it indicates an issue with the engine’s ability to start. This can lead to a no-start situation, leaving you stranded.

How to Clear the Code: After fixing the problem, clear the code with an OBD-II scanner. Disconnecting the battery may reset the code and the ECM’s learned data, but it is not the preferred method. It’s important to address the underlying issue and use a proper scan tool to reset the code.

Tools Needed to Use:

  1. OBD-II scanner – to read and clear the code
  2. Multimeter – to test the battery, starter motor, and other electrical components
  3. Basic hand tools – for removing and installing components
  4. Specialized tools – for diagnosing and repairing ECM or starter motor issues (if applicable)

 

DTC Code: P0171 – System Too Lean (Bank 1)

 

Description: The P0171 code indicates that the air-fuel mixture in Bank 1 (the side of the engine with cylinder 1) is too lean, meaning there is too much air and not enough fuel. The Engine Control Module (ECM) monitors the air-fuel ratio and triggers the code when it detects an imbalance.

Symptoms:

  • Rough idle
  • Hesitation or stalling during acceleration
  • Reduced fuel efficiency
  • Loss of power
  • Illuminated Check Engine Light (CEL) or Malfunction Indicator Lamp (MIL)

Cause:

  • Vacuum leaks (hoses, intake manifold gaskets, etc.)
  • Faulty Mass Air Flow (MAF) sensor
  • Faulty oxygen sensor (pre-catalytic converter)
  • Dirty or clogged fuel injectors
  • Low fuel pressure (due to a faulty fuel pump or fuel pressure regulator)
  • Faulty ECM

Possible Location:

  • Vacuum hoses and connections
  • Intake manifold gaskets
  • Mass Air Flow sensor
  • Oxygen sensor (pre-catalytic converter)
  • Fuel injectors
  • Fuel pump and fuel pressure regulator
  • ECM

How to Fix the Problem:

  1. Inspect vacuum hoses and connections for damage or leaks. Repair or replace as needed.
  2. Check the intake manifold gaskets for leaks. Replace if necessary.
  3. Test the Mass Air Flow sensor with a multimeter or scan tool. Clean or replace if necessary.
  4. Inspect and test the pre-catalytic converter oxygen sensor. Replace if faulty.
  5. Clean or replace dirty or clogged fuel injectors.
  6. Test the fuel pump and fuel pressure regulator for proper operation. Replace if necessary.
  7. Inspect and test the ECM for proper operation. Replace if necessary.

How Difficult to Fix: Moderate. Some steps can be performed by DIYers with basic automotive knowledge. However, diagnosing and repairing issues with the ECM or fuel system may require specialized tools and expertise.

Can You Drive With This Code: Driving with this code is not recommended, as it can lead to poor engine performance, reduced fuel efficiency, and potential damage to the catalytic converter.

How to Clear the Code: After fixing the problem, clear the code with an OBD-II scanner. Disconnecting the battery may reset the code and the ECM’s learned data, but it is not the preferred method. It’s important to address the underlying issue and use a proper scan tool to reset the code.

Tools Needed to Use:

  1. OBD-II scanner – to read and clear the code
  2. Multimeter – to test electrical components such as the MAF sensor and oxygen sensor
  3. Basic hand tools – for removing and installing components
  4. Specialized tools – for diagnosing and repairing ECM or fuel system issues (if applicable)
  5. Fuel pressure gauge – to test fuel pressure (if necessary)

 

DTC Code: C1201 – Engine Control System Malfunction

 

Description: The C1201 code indicates that the Engine Control Module (ECM) has detected a malfunction in the engine control system, which can affect the operation of the Anti-Lock Brake System (ABS) and Traction Control System (TCS). This code is typically triggered when there is an issue with the engine that could impact vehicle stability.

Symptoms:

  • Reduced engine performance
  • Illuminated Check Engine Light (CEL) or Malfunction Indicator Lamp (MIL)
  • ABS and/or TCS warning light
  • Poor acceleration
  • Rough idle

Cause:

  • Faulty engine sensors (e.g., Mass Air Flow sensor, oxygen sensor, etc.)
  • Vacuum leaks
  • Ignition system issues
  • Fuel system problems
  • Faulty ECM

Possible Location:

  • Engine sensors
  • Vacuum hoses and connections
  • Ignition system components
  • Fuel system components
  • ECM

How to Fix the Problem:

  1. Use an OBD-II scanner to check for any engine-related DTC codes that may provide more specific information about the issue.
  2. Inspect engine sensors for damage or malfunction. Repair or replace as needed.
  3. Check vacuum hoses and connections for damage or leaks. Repair or replace as necessary.
  4. Inspect the ignition system components (spark plugs, ignition coils, etc.) for damage or wear. Replace if necessary.
  5. Diagnose and repair any fuel system issues (e.g., clogged fuel injectors, faulty fuel pump, etc.).
  6. Test the ECM for proper operation. Replace if necessary.

How Difficult to Fix: Moderate to Difficult. Some steps can be performed by DIYers with basic automotive knowledge, while others may require specialized tools and expertise, particularly when diagnosing and repairing issues with the ECM.

Can You Drive With This Code: Driving with this code is not recommended, as it can lead to poor engine performance, reduced fuel efficiency, and compromised safety features such as ABS and TCS.

How to Clear the Code: After fixing the problem, clear the code with an OBD-II scanner. Disconnecting the battery may reset the code and the ECM’s learned data, but it is not the preferred method. It’s important to address the underlying issue and use a proper scan tool to reset the code.

Tools Needed to Use:

  1. OBD-II scanner – to read and clear the code
  2. Multimeter – to test electrical components such as engine sensors
  3. Basic hand tools – for removing and installing components
  4. Specialized tools – for diagnosing and repairing ECM issues (if applicable)
  5. Fuel pressure gauge – to test fuel pressure (if necessary)

 

DTC Code: C1301 – Brake Hydraulic Pressure Sensor Circuit Failure

 

Description: The C1301 code indicates that there is a problem with the brake hydraulic pressure sensor circuit. This sensor measures the hydraulic pressure in the brake system and sends that information to the Anti-Lock Brake System (ABS) module. A fault in this circuit can lead to poor braking performance and ABS malfunction.

Symptoms:

  • ABS warning light illuminated
  • Traction Control System (TCS) warning light illuminated
  • Reduced braking performance
  • Brake pedal feels harder or softer than usual
  • Brake system warning light illuminated (in some cases)

Cause:

  • Faulty brake hydraulic pressure sensor
  • Damaged or corroded wiring or connectors in the sensor circuit
  • Low brake fluid level
  • Air in the brake system
  • Malfunctioning ABS module

Possible Location:

  • Brake hydraulic pressure sensor (located in the brake system, often near the master cylinder)
  • Wiring harnesses connected to the brake hydraulic pressure sensor
  • Brake fluid reservoir
  • ABS module

How to Fix the Problem:

  1. Inspect the brake hydraulic pressure sensor and its wiring for damage, corrosion, or loose connections. Repair or replace as needed.
  2. Test the brake hydraulic pressure sensor with a multimeter to ensure it is functioning properly. Replace the sensor if faulty.
  3. Check the brake fluid level and top off if necessary. Inspect for any leaks in the brake system.
  4. Bleed the brake system to remove any air that may be trapped in the lines.
  5. Inspect and test the ABS module for proper operation. Repair or replace if necessary.

How Difficult to Fix: Moderate. Some steps, such as checking the brake fluid level and bleeding the brake system, can be performed by DIYers with basic automotive knowledge. However, diagnosing and repairing issues with the brake hydraulic pressure sensor or ABS module may require specialized tools and expertise.

Can You Drive With This Code: It is not recommended to drive with this code, as it can lead to reduced braking performance and compromised safety features such as ABS and TCS.

How to Clear the Code: After fixing the problem, clear the code with an OBD-II scanner specifically designed to read ABS codes. Disconnecting the battery may reset the code and the ABS module’s learned data, but it is not the preferred method. It’s important to address the underlying issue and use a proper scan tool to reset the code.

Tools Needed to Use:

  1. OBD-II scanner with ABS capabilities – to read and clear the code
  2. Multimeter – to test the brake hydraulic pressure sensor and wiring
  3. Basic hand tools – for removing and installing components
  4. Brake bleeder kit – for bleeding the brake system
  5. Specialized tools – for diagnosing and repairing ABS module issues (if applicable)

 

DTC Code: B150A – Front Pretensioner Squib LH Circuit Malfunction

 

Description: The B150A code indicates that there is a malfunction in the front pretensioner squib (igniter) circuit for the left-hand (driver’s side) seat belt. The pretensioner is a crucial part of the seat belt system that tightens the belt in the event of a collision, helping to reduce the risk of injury.

Symptoms:

  • Airbag warning light illuminated
  • Seat belt warning light illuminated
  • Seat belt pretensioner not working properly during a collision

Cause:

  • Faulty front seat belt pretensioner squib (igniter)
  • Damaged or corroded wiring or connectors in the pretensioner circuit
  • Faulty Airbag Control Module (ACM)

Possible Location:

    • Front left seat belt pretensioner
    • Wiring harnesses connected to the pretensioner
    • Airbag Control Module

How to Fix the Problem:

  1. Inspect the front left seat belt pretensioner and its wiring for damage, corrosion, or loose connections. Repair or replace as needed.
  2. Test the pretensioner squib with a multimeter or scan tool to ensure it is functioning properly. Replace the pretensioner if faulty.
  3. Inspect and test the Airbag Control Module for proper operation. Repair or replace if necessary.

How Difficult to Fix: Moderate. Some steps can be performed by DIYers with basic automotive knowledge. However, diagnosing and repairing issues with the airbag control module and pretensioner squib may require specialized tools and expertise.

Can You Drive With This Code: While it may be possible to drive with this code, it is not recommended as it can compromise the safety of the driver during a collision due to a malfunctioning seat belt pretensioner.

How to Clear the Code: After fixing the problem, clear the code with an OBD-II scanner specifically designed to read airbag (SRS) codes. Disconnecting the battery may reset the code and the Airbag Control Module’s learned data, but it is not the preferred method. It’s important to address the underlying issue and use a proper scan tool to reset the code.

Tools Needed to Use:

  1. OBD-II scanner with SRS capabilities – to read and clear the code
  2. Multimeter – to test the pretensioner squib and wiring
  3. Basic hand tools – for removing and installing components
  4. Specialized tools – for diagnosing and repairing Airbag Control Module issues (if applicable)

WORDS FROM ERWIN SALARDA

Understanding the top six most common OBD-II trouble codes for Toyota Avalon vehicles is key to proper maintenance and timely repairs. By staying aware of these issues and their respective solutions, you can prolong the life of your Avalon and enhance its overall performance. Remember that addressing problems early on can save you from expensive repairs down the line.