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AutoCodes – Toyota – P0301 Toyota

P0301 Toyota Code - Cylinder 1 Misfire Detected

Quick Answer

When the engine misfires, high concentrations of Hydrocarbons (HC) enter the exhaust gas. Common causes include Intake air leak, Faulty spark plug #1, Faulty ignition coil #1. 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
P0301 Toyota indicates Cylinder 1 Misfire Detected.
Common causes
Common causes include Intake air leak, Faulty spark plug #1, Faulty ignition coil #1.
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 149,069
How popular is this code, among other codes? Medium
What is this?
Table of contents Created and updated by William Orellana on Jul 17, 2023
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Code P0301 Toyota Description

When the engine misfires, high concentrations of Hydrocarbons (HC) enter the exhaust gas. Extremely high hydrocarbon concentration levels can cause an increase in exhaust emission levels. Extremely high concentrations of hydrocarbons can also cause increases in the three-way catalytic converter temperature, which may cause damage to the three-way catalytic converter. To prevent this increase in emissions and to limit the possibility of thermal damage, the Engine Control Module (ECM) monitors the misfire count. When the temperature of the three-way catalytic converter reaches the point of thermal degradation, the ECM blinks the MIL. To monitor misfires, the ECM uses both the camshaft position sensor and the crankshaft position sensor. The camshaft position sensor is used to identify any misfiring cylinders and the crankshaft position sensor is used to measure variations in the crankshaft rotation speed. Misfires are counted when the crankshaft rotation speed variations exceed predetermined thresholds. If the misfire count exceeds the threshold levels and could cause emission control system performance deterioration, the ECM illuminates the MIL and stores a Diagnostic Trouble Code (DTC).
OBDII Code P0301 Toyota - Cylinder 1 Misfire Detected - AutoCodes.com
P0301 Toyota Code - Cylinder 1 Misfire Detected
What does this mean?

What are the Possible Causes of the DTC P0301 Toyota?

  • Intake air leak
  • Faulty spark plug #1
  • Faulty ignition coil #1
  • Clogged or faulty fuel injector #1
  • Fuel injectors #1 harness is open or shorted
  • Fuel Injectors #1 circuit poor electrical connection
  • Ignition coils #1 harness is open or shorted
  • Ignition coils #1 circuit poor electrical connection
  • Incorrect Fuel pressure
  • Faulty Mass Air Flow (MAF) Sensor
  • Faulty Engine Control Module (ECM)
  • Faulty Engine Coolant Temperature (ECT) Sensor

How to Fix the DTC P0301 Toyota?

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

The P0301 code means that cylinder #1 is misfiring or is randomly misfiring. Start by checking for intake leaks and if no leaks are found the next step is to replace the spark plugs on cylinder #1. If the problem persists more tests need to be done to diagnose the problem. See "Possible Causes" for the most common problems.









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What is the Cost to Diagnose the Code?

Labor: 1.0

To diagnose the P0301 Toyota 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 P0301 Toyota code?

Need more information on how to fix the P0301 Toyota code? Get Access to Factory Service Manuals

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Information for Specific Toyota Models

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 P0301 Toyota Code

1. What are the common symptoms of an OBDII code P0301 in a Toyota?

Common symptoms include rough idling, loss of power, engine misfiring, and increased fuel consumption.

2. What are the typical causes of a cylinder 1 misfire in a Toyota?

Common causes include faulty spark plugs, ignition coil issues, vacuum leaks, fuel injector problems, or low compression in the cylinder.

3. How can I diagnose the source of a cylinder 1 misfire in my Toyota?

You can diagnose the issue by checking spark plugs, inspecting the ignition coil, performing a compression test, looking for vacuum leaks, or using a scan tool to monitor live data.

4. Can a dirty fuel injector cause a cylinder 1 misfire in a Toyota?

Yes, a dirty or clogged fuel injector can lead to a cylinder 1 misfire by disrupting the proper fuel delivery to the cylinder.

5. How should I address an OBDII code P0301 in my Toyota?

Start by checking and replacing the spark plugs, inspecting the ignition coil, verifying fuel injector function, and addressing any vacuum leaks.

6. Is it safe to continue driving with a cylinder 1 misfire in my Toyota?

It is not recommended to drive with a misfire as it can cause further damage to the engine and emission control components. Seek repairs promptly.

7. Can bad gasoline trigger a cylinder 1 misfire in a Toyota?

Poor-quality or contaminated gasoline can potentially lead to a misfire by affecting fuel combustion and engine performance.

8. Why is it important to address an OBDII code P0301 promptly in a Toyota?

Ignoring a cylinder 1 misfire can result in decreased fuel efficiency, engine damage, catalytic converter failure, and potentially unsafe driving conditions.

9. Will resetting the OBDII code P0301 in a Toyota fix the issue?

Resetting the code without addressing the underlying problem will not solve the misfire. It is crucial to diagnose and repair the root cause of the issue.

10. How can regular maintenance help prevent a cylinder 1 misfire in a Toyota?

Regularly changing spark plugs, inspecting ignition components, using quality fuel, and following the manufacturer's maintenance schedule can help prevent misfires.

Discuss the causes and fixes for P0301 Toyota OBDII Code

Submit a New Comment

  • best advice ever,mine was a bad #1 injector, thank you

    Reply to Comment

  • A friend found water under cylinder 1 coil. May be associated with recent engine wash. Dried out the area and code went away. Will probably add some silicone around coil for a better seal.

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  • I originally had Po138, P0607, and P0301. I replaced spark plugs and moved ignition coils to see if misfire followed. It did not. I also replaced my 12 volt battery for 2012 Prius because mine had gone dead. Then I reset the codes and it ran great for a day. Today it started misfiring again and code P0301 came back. The other two codes did not. The misfiring is getting worse.

    Reply to Comment

  • HI it hapend to me the same problems so what was the problem? thank you

    Reply to Comment

  • Can I drive my toyota venza 4 cylinder, with 1 cylinder is not working how many miles can I drive.

    Reply to Comment

  • I don't recommend driving it at all. Driving your vehicle in that condition can damage the Catalytic Converter and overheat the engine. It's difficult to say how many miles it will take to damage the catalytic converter and overheat.

    Reply to Comment
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