Top 10 Toyota Highlander DTC Codes Explained
When your Toyota Highlander’s check engine light turns on, it’s usually accompanied by a trouble code stored in the vehicle’s onboard diagnostic system. These codes, also known as DTC codes, can help identify the cause of the issue and guide you in fixing it. In this article, we’ll discuss the top 10 most common DTC codes for Toyota Highlander vehicles, including symptoms, causes, and solutions.
OBD DTC P0174: System too Lean (Bank 2)
Symptoms: Decreased fuel efficiency, rough idle, hesitation or stalling when accelerating, decreased power
Cause: This code indicates that the engine control module (ECM) has detected a lean air/fuel mixture in the second bank of cylinders. This could be due to a vacuum leak, a clogged air filter, a malfunctioning mass air flow sensor, or a faulty fuel injector.
Posible Location: Engine
How to Fix the Problem: Inspect air intake system for leaks, replace air filter, clean or replace mass air flow sensor, replace or repair fuel injectors, replace vacuum hoses
How Difficult to Fix: Moderate
Can You Drive With This Code: Driving with this code should not be dangerous but it can cause the vehicle to perform poorly and decrease fuel efficiency.
How to Clear the Code: The code can be cleared using an OBD-II scanner or disconnecting the vehicle’s battery for a few minutes.
Hand Tools Need to use: Basic hand tools, OBD-II scanner
OBD DTC P0300: Random/Multiple Cylinder Misfire Detected
Symptoms: Engine misfire, rough running engine, decreased power, increased emissions
Cause: This code indicates that the engine control module (ECM) has detected a misfire in multiple cylinders. This could be due to a spark plug problem, a fuel injector problem, a vacuum leak, or an issue with the ignition system.
Posible Location: Engine
How to Fix the Problem: Inspect and replace spark plugs, inspect and replace fuel injectors, inspect vacuum hoses, inspect ignition system components
How Difficult to Fix: Moderate
Can You Drive With This Code: Driving with this code should not be dangerous but it can cause the vehicle to perform poorly and increase emissions.
How to Clear the Code: The code can be cleared using an OBD-II scanner or disconnecting the vehicle’s battery for a few minutes.
Hand Tools Need to use: Basic hand tools, OBD-II scanner
OBD DTC P1135: Air/Fuel Ratio Sensor Heater Circuit Malfunction (Bank 1 Sensor 1)
Symptoms: Engine warning light, decreased fuel efficiency, decreased engine performance
Cause: This code indicates that there is a problem with the air/fuel ratio sensor heater circuit in the first bank of cylinders, which can cause the sensor to provide incorrect readings to the engine control module (ECM).
Posible Location: Engine
How to Fix the Problem: Replace the air/fuel ratio sensor, inspect and repair the sensor’s wiring and connections
How Difficult to Fix: Moderate
Can You Drive With This Code: Driving with this code should not be dangerous but it can cause the vehicle to perform poorly and decrease fuel efficiency.
How to Clear the Code: The code can be cleared using an OBD-II scanner or disconnecting the vehicle’s battery for a few minutes.
Hand Tools Need to use: Basic hand tools, OBD-II scanner
OBD DTC C1201: Engine Control System Malfunction
Symptoms: Engine warning light, decreased engine performance, decreased fuel efficiency
Cause: This code indicates a malfunction in the engine control system, which can be caused by a variety of issues, including a faulty engine control module (ECM), a problem with the wiring, or a sensor malfunction.
Posible Location: Engine, engine control module
How to Fix the Problem: Inspect and repair wiring, replace failed sensors, replace engine control module (ECM)
How Difficult to Fix: Hard
Can You Drive With This Code: Driving with this code couldbe dangerous and can cause the vehicle to perform poorly and decrease fuel efficiency. It is recommended to have the issue repaired as soon as possible.
How to Clear the Code: The code can be cleared using an OBD-II scanner or disconnecting the vehicle’s battery for a few minutes.
Hand Tools Need to use: Basic hand tools, OBD-II scanner
OBD DTC P1155: Air/Fuel Ratio Sensor Heater Circuit Malfunction (Bank 2 Sensor 1)
Symptoms: Engine warning light, decreased fuel efficiency, decreased engine performance
Cause: This code indicates that there is a problem with the air/fuel ratio sensor heater circuit in the second bank of cylinders, which can cause the sensor to provide incorrect readings to the engine control module (ECM).
Posible Location: Engine
How to Fix the Problem: Replace the air/fuel ratio sensor, inspect and repair the sensor’s wiring and connections
How Difficult to Fix: Moderate
Can You Drive With This Code: Driving with this code should not be dangerous but it can cause the vehicle to perform poorly and decrease fuel efficiency.
How to Clear the Code: The code can be cleared using an OBD-II scanner or disconnecting the vehicle’s battery for a few minutes.
Hand Tools Need to use: Basic hand tools, OBD-II scanner
OBD DTC P1604: Immobilizer System Malfunction
Symptoms: Engine warning light, engine will not start or run
Cause: This code indicates a malfunction in the immobilizer system, which is responsible for preventing unauthorized starting of the vehicle. This could be due to a problem with the immobilizer system’s control module, a faulty key, or a problem with the wiring.
Posible Location: Engine, immobilizer system control module, key
How to Fix the Problem: Replace the immobilizer system control module, replace the key, inspect and repair the wiring
How Difficult to Fix: Hard
Can You Drive With This Code: No, the vehicle will not start or run with this code.
How to Clear the Code: The code can be cleared using an OBD-II scanner or disconnecting the vehicle’s battery for a few minutes.
Hand Tools Need to use: Basic hand tools, OBD-II scanner
OBD DTC P0171: System too Lean (Bank 1)
Symptoms: Decreased fuel efficiency, rough idle, hesitation or stalling when accelerating, decreased power
Cause: This code indicates that the engine control module (ECM) has detected a lean air/fuel mixture in the first bank of cylinders. This could be due to a vacuum leak, a clogged air filter, a malfunctioning mass air flow sensor, or a faulty fuel injector.
Posible Location: Engine
How to Fix the Problem: Inspect air intake system for leaks, replace air filter, clean or replace mass air flow sensor, replace or repair fuel injectors, replace vacuum hoses
How Difficult to Fix: Moderate
Can You Drive With This Code: Driving with this code should not be dangerous but it can cause the vehicle to perform poorly and decrease fuel efficiency.
How to Clear the Code: The code can be cleared using an OBD-II scanner or disconnecting the vehicle’s battery for a few minutes.
Hand Tools Need to use: Basic hand tools, OBD-II scanner
OBD DTC P0301: Cylinder 1 Misfire Detected
Symptoms: Engine misfire, rough running engine, decreased power, increased emissions
Cause: This code indicates that the engine control module (ECM) has detected a misfire in the first cylinder. This could be due to a spark plug problem, a fuel injector problem, a vacuum leak, or an issue with theignition system.
Posible Location: Engine
How to Fix the Problem: Inspect and replace spark plugs, inspect and replace fuel injectors, inspect vacuum hoses, inspect ignition system components
How Difficult to Fix: Moderate
Can You Drive With This Code: Driving with this code should not be dangerous but it can cause the vehicle to perform poorly and increase emissions.
How to Clear the Code: The code can be cleared using an OBD-II scanner or disconnecting the vehicle’s battery for a few minutes.
Hand Tools Need to use: Basic hand tools, OBD-II scanner
OBD DTC P0325: Knock Sensor Circuit Malfunction (Bank 1 or Single Sensor)
Symptoms: Engine warning light, decreased engine performance, decreased fuel efficiency, knocking or pinging sounds from the engine
Cause: This code indicates that there is a problem with the knock sensor circuit, which is responsible for detecting knocking or pinging sounds in the engine. This could be due to a faulty knock sensor, a problem with the wiring, or an issue with the engine control module (ECM).
Posible Location: Engine, knock sensor, engine control module
How to Fix the Problem: Replace the knock sensor, inspect and repair the wiring, replace the engine control module (ECM)
How Difficult to Fix: Moderate
Can You Drive With This Code: Driving with this code should not be dangerous but it can cause the vehicle to perform poorly and decrease fuel efficiency.
How to Clear the Code: The code can be cleared using an OBD-II scanner or disconnecting the vehicle’s battery for a few minutes.
Hand Tools Need to use: Basic hand tools, OBD-II scanner
OBD DTC P0135: Oxygen Sensor Heater Circuit Malfunction (Bank 1 Sensor 1)
Symptoms: Engine warning light, decreased fuel efficiency, decreased engine performance
Cause: This code indicates that there is a problem with the oxygen sensor heater circuit in the first bank of cylinders, which can cause the sensor to provide incorrect readings to the engine control module (ECM).
Posible Location: Engine
How to Fix the Problem: Replace the oxygen sensor, inspect and repair the sensor’s wiring and connections
How Difficult to Fix: Moderate
Can You Drive With This Code: Driving with this code should not be dangerous but it can cause the vehicle to perform poorly and decrease fuel efficiency.
How to Clear the Code: The code can be cleared using an OBD-II scanner or disconnecting the vehicle’s battery for a few minutes.
Hand Tools Need to use: Basic hand tools, OBD-II scanner.
WORDS FROM ERWIN
It’s important to note that while these top 10 most common DTC codes can give you a good starting point in troubleshooting engine issues, they may not cover all possible scenarios. If you’re unsure about what’s causing your Toyota Highlander’s check engine light to turn on, it’s always best to consult a professional mechanic.