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P0304 2017 Toyota RAV4 Code - Cylinder 4 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 #4, Faulty ignition coil #4. 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
P0304 2017 Toyota RAV4 indicates Cylinder 4 Misfire Detected.
Common causes
Common causes include Intake air leak, Faulty spark plug #4, Faulty ignition coil #4.
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 488
How popular is this code, among other codes? Low
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Table of contents Created and updated by William Orellana on Aug 25, 2022
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Code P0304 2017 Toyota RAV4 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 P0304 2017 Toyota RAV4 - Cylinder 4 Misfire Detected - AutoCodes.com
P0304 2017 Toyota RAV4 Code - Cylinder 4 Misfire Detected
What does this mean?

What are the Possible Causes of the DTC P0304 2017 Toyota RAV4?

  • Intake air leak
  • Faulty spark plug #4
  • Faulty ignition coil #4
  • Clogged or faulty fuel injector #4
  • Fuel injectors #4 harness is open or shorted
  • Fuel Injectors #4 circuit poor electrical connection
  • Ignition coils #4 harness is open or shorted
  • Ignition coils #4 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 P0304 2017 Toyota RAV4?

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 P0304 code means that cylinder #4 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 #4. If the problem persists more tests need to be done to diagnose the problem. See "Possible Causes" for the most common problems.

What is the Cost to Diagnose the Code?

Labor: 1.0

To diagnose the P0304 2017 Toyota RAV4 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 P0304 2017 Toyota RAV4 code?

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Need Help with the Code?

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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 P0304 2017 Toyota RAV4 Code

1. What does OBDII code P0304 on a 2017 Toyota RAV4 mean?

- OBDII code P0304 indicates a "Cylinder 4 Misfire Detected" in the engine of a 2017 Toyota RAV4.

2. What are the common symptoms of a cylinder 4 misfire in a 2017 Toyota RAV4?

- Common symptoms include rough idling, loss of power, engine shaking, poor fuel economy, and potentially a blinking check engine light.

3. What are the possible causes of a misfire in cylinder 4 of a 2017 Toyota RAV4?

- Common causes may include faulty spark plugs, ignition coils, fuel injectors, vacuum leaks, low compression, or issues with the engine's computer system.

4. How can I diagnose the cause of a cylinder 4 misfire in my 2017 Toyota RAV4?

- Diagnosis typically involves checking spark plugs, ignition coils, fuel injectors, vacuum lines, compression levels, and using a scan tool to analyze live engine data.

5. Can a dirty or clogged fuel injector cause a cylinder 4 misfire in a 2017 Toyota RAV4?

- Yes, a dirty or clogged fuel injector can disrupt the fuel delivery to cylinder 4, leading to a misfire.

6. Do I need to replace all spark plugs if only cylinder 4 is misfiring in my 2017 Toyota RAV4?

- It's recommended to replace all spark plugs at the same time to ensure consistent performance across all cylinders.

7. How important is it to address a cylinder 4 misfire in a 2017 Toyota RAV4 promptly?

- Addressing a misfire promptly is crucial to prevent potential damage to the catalytic converter and other engine components.

8. Can a bad ignition coil cause a cylinder 4 misfire in a 2017 Toyota RAV4?

- Yes, a faulty ignition coil can lead to a misfire in cylinder 4 by disrupting the spark delivery to the spark plug.

9. How can I prevent future cylinder misfires in my 2017 Toyota RAV4?

- Regular maintenance, such as changing spark plugs and inspecting ignition components, can help prevent future misfires in your vehicle.

10. Is it safe to drive my 2017 Toyota RAV4 with a cylinder 4 misfire?

- It is not recommended to drive with a cylinder 4 misfire as it can lead to further engine damage and potential safety hazards.

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