AutoCodes – Toyota – P0304 2007 Toyota Prius

P0304 2007 Toyota Prius Code - Cylinder 4 Misfire Detected

Quick Answer

When a misfire occurs, engine speed will fluctuate. Common causes include Faulty Spark Plug #4, Clogged or faulty Fuel Injector #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 2007 Toyota Prius indicates Cylinder 4 Misfire Detected.
Common causes: Common causes include Faulty Spark Plug #4, Clogged or faulty Fuel Injector #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 5,652

How popular is this code, among other codes? Low

Repair Importance Level

Urgent (Diagnose now) (3 / 3)

Repair Difficulty Level

Advanced (Pro) (3 / 3)

What is this?

Table of contents Created and updated by William Orellana on Jun 14, 2020

Description
Step-by-Step Diagnostic Guide
Possible Causes
How To Fix
Tech Notes
Cost to Diagnose
FAQs
Comments
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Code P0304 2007 Toyota Prius Description

When a misfire occurs, engine speed will fluctuate. If the engine speed fluctuates enough to cause the Crankshaft Position (CKP) sensor signal to vary, the Engine Control Module (ECM) can determine that a misfire is occurring.

OBDII Code P0304 2007 Toyota Prius - Cylinder 4 Misfire Detected - AutoCodes.com — P0304 2007 Toyota Prius Code - Cylinder 4 Misfire Detected

What does this mean?

What are the Possible Causes of the DTC P0304 2007 Toyota Prius?

Faulty Spark Plug #4
Clogged or faulty Fuel Injector #4
Faulty Ignition Coil #4
Fuel Injector #4 harness is open or shorted
Fuel Injector #4 circuit poor electrical connection
Ignition Coil #4 harness is open or shorted
Ignition Coil #4 circuit poor electrical connection
Insufficient cylinder 4 compression
Incorrect fuel pressure
Intake air leak
Valve timing
Mass air flow meter
Engine coolant temperature sensor
ECM

How to Fix the DTC P0304 2007 Toyota Prius?

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 the 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 needs to be done to diagnose problem, see "Possible Causes"

What is the Cost to Diagnose the Code?

Labor: 1.0

To diagnose the P0304 2007 Toyota Prius 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 2007 Toyota Prius 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 2007 Toyota Prius Code

1. What are common symptoms of OBDII code P0304 in a 2007 Toyota Prius?

- Common symptoms include engine misfires, rough idling, loss of power, and potential increase in fuel consumption.

2. What are the possible causes of a cylinder 4 misfire detected in a 2007 Toyota Prius?

- Possible causes include faulty spark plugs, ignition coils, fuel injectors, vacuum leaks, low compression, or issues with the engine control module.

3. How can I diagnose the cause of the cylinder 4 misfire in my 2007 Toyota Prius?

- You can diagnose the issue by checking the spark plugs, ignition coils, fuel injectors, vacuum lines, and performing a compression test on cylinder 4.

4. Can a dirty air filter cause OBDII code P0304 in a 2007 Toyota Prius?

- Yes, a dirty air filter can disrupt the air-fuel mixture and lead to a cylinder 4 misfire detected code.

5. Are there any DIY repair tips for addressing a cylinder 4 misfire in a 2007 Toyota Prius?

- DIY repair tips include replacing spark plugs, ignition coils, or fuel injectors, checking for vacuum leaks, and ensuring proper compression in cylinder 4.

6. Is it safe to continue driving my 2007 Toyota Prius with OBDII code P0304?

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

7. How much does it typically cost to repair OBDII code P0304 in a 2007 Toyota Prius?

- The cost of repair can vary depending on the exact cause of the misfire, but it can range from $100 for simple fixes to over $500 for more complex issues.

8. Can bad fuel quality trigger OBDII code P0304 in a 2007 Toyota Prius?

- Yes, bad fuel quality or contaminated fuel can contribute to cylinder misfires and trigger the P0304 code.

9. Will resetting the OBDII code P0304 in a 2007 Toyota Prius make the issue go away?

- Resetting the code may temporarily clear the check engine light, but it will not fix the underlying issue causing the cylinder 4 misfire.

10. How often should I perform maintenance to prevent OBDII code P0304 in my 2007 Toyota Prius?

- Regular maintenance, including changing spark plugs, inspecting ignition components, and addressing any engine issues promptly, can help prevent cylinder misfires and the P0304 code.