AutoCodes – Scion – P0304 2005 Scion xB

P0304 2005 Scion xB Code - Cylinder 4 Misfire Detected

Quick Answer

When the engine misfires, high concentrations of hydrocarbons (HC) enter the exhaust gas. Common causes include Faulty spark plug (s), Faulty ignition coil (s), Clogged or faulty fuel injector (s). 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 2005 Scion xB indicates Cylinder 4 Misfire Detected.
Common causes: Common causes include Faulty spark plug (s), Faulty ignition coil (s), Clogged or faulty fuel injector (s).
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 4,965

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 2005 Scion xB Description

When the engine misfires, high concentrations of hydrocarbons (HC) enter the exhaust gas. Extremely high HC concentration levels can cause increases in exhaust emission levels. High concentrations of HC can also cause increases in the Three-Way Catalytic Converter (TWC) temperature, which may cause damage to the TWC. To prevent these increases in emissions and to limit the possibility of thermal damage, the ECM monitors the misfire rate. When the temperature of the TWC reaches the point of thermal degradation, the ECM blinks the MIL. To monitor misfires, the ECM uses both the Camshaft Position (CMP) sensor and the Crankshaft Position (CKP) sensor. The CMP sensor is used to identify any misfiring cylinders and the CKP 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 exceeds the threshold levels, and could cause emission deterioration, the ECM illuminates the MIL and sets a DTC.

OBDII Code P0304 2005 Scion xB - Cylinder 4 Misfire Detected - AutoCodes.com — P0304 2005 Scion xB Code - Cylinder 4 Misfire Detected

What does this mean?

What are the Possible Causes of the DTC P0304 2005 Scion xB?

Faulty spark plug (s)
Faulty ignition coil (s)
Clogged or faulty fuel injector (s)
Intake air leak
Fuel injectors harness is open or shorted
Fuel Injectors circuit poor electrical connection
Ignition coils harness is open or shorted
Ignition coils circuit poor electrical connection
Insufficient cylinders compression
Incorrect fuel pressure
Mass air flow meter
Engine coolant temperature sensor
Valve clearance
Valve timing
ECM

How to Fix the DTC P0304 2005 Scion xB?

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 2005 Scion xB 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.

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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 2005 Scion xB Code

1. What are common symptoms of OBDII code P0304 on a 2005 Scion xB?

- Common symptoms include engine misfires, rough idling, loss of power, and potential engine vibrations.

2. What are the possible causes of OBDII code P0304 on a 2005 Scion xB?

- The most common causes are faulty spark plugs, ignition coils, fuel injectors, vacuum leaks, or a problem with the cylinder 4 itself.

3. How can I diagnose the cause of OBDII code P0304 on my 2005 Scion xB?

- You can diagnose the issue by checking the spark plugs, ignition coils, fuel injectors, vacuum lines, compression in cylinder 4, and performing a visual inspection for any visible issues.

4. Can driving with OBDII code P0304 on a 2005 Scion xB cause further damage?

- Driving with a misfire can potentially damage the catalytic converter over time. It is recommended to address the issue promptly to avoid additional problems.

5. How can I repair OBDII code P0304 on my 2005 Scion xB?

- Depending on the cause, you may need to replace the spark plugs, ignition coils, fuel injectors, or repair any vacuum leaks. It's important to address the specific issue causing the misfire.

6. Is it safe to continue driving my 2005 Scion xB with OBDII code P0304?

- It is not recommended to drive with a misfire as it can lead to further damage and potential safety issues. It's best to address the problem as soon as possible.

7. Will resetting the OBDII code P0304 on my 2005 Scion xB make it go away?

- Resetting the code may temporarily remove the Check Engine Light, but it will not fix the underlying issue causing the misfire. The problem will likely return if not properly addressed.

8. How much does it typically cost to repair OBDII code P0304 on a 2005 Scion xB?

- The cost of repair can vary depending on the specific cause of the misfire. It may range from a simple fix like replacing spark plugs to a more complex issue like a faulty fuel injector.

9. Can bad gasoline cause OBDII code P0304 on a 2005 Scion xB?

- Poor quality or contaminated gasoline can potentially lead to misfires, including OBDII code P0304. It's important to use high-quality fuel to prevent issues.

10. Could a faulty oxygen sensor trigger OBDII code P0304 on a 2005 Scion xB?

- While a faulty oxygen sensor is not a common cause of cylinder misfires, it can indirectly impact engine performance and potentially contribute to the issue.