AutoCodes – Scion – P0304 2007 Scion xB

P0304 2007 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 2007 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 2,911

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 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 2007 Scion xB - Cylinder 4 Misfire Detected - AutoCodes.com — P0304 2007 Scion xB Code - Cylinder 4 Misfire Detected

What does this mean?

What are the Possible Causes of the DTC P0304 2007 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 2007 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 2007 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 2007 Scion xB Code

1. What are the common symptoms of OBDII code P0304 in a 2007 Scion xB?

A: Common symptoms of P0304 (Cylinder 4 Misfire Detected) in a 2007 Scion xB may include rough idling, loss of power, engine misfiring, and a noticeable decrease in fuel efficiency.

2. What are some possible causes of OBDII code P0304 in a 2007 Scion xB?

A: Possible causes of P0304 in a 2007 Scion xB include faulty spark plugs, a malfunctioning ignition coil, low fuel pressure, a vacuum leak, or a problem with the fuel injector for cylinder 4.

3. How can I diagnose the cause of OBDII code P0304 in my 2007 Scion xB?

A: To diagnose the cause of P0304 in a 2007 Scion xB, you can start by checking the spark plugs, ignition coil, fuel injector, and fuel pressure. Additionally, performing a compression test on cylinder 4 can help identify any internal engine issues.

4. Can driving with OBDII code P0304 in a 2007 Scion xB cause further damage?

A: Continuing to drive with P0304 in a 2007 Scion xB can potentially cause damage to the catalytic converter, oxygen sensor, and other engine components due to unburned fuel entering the exhaust system.

5. How can I repair OBDII code P0304 in my 2007 Scion xB?

A: Repairing P0304 in a 2007 Scion xB typically involves replacing the spark plugs, ignition coil, fuel injector, or addressing any other underlying issues causing the misfire in cylinder 4.

6. Is it safe to continue driving my 2007 Scion xB with OBDII code P0304?

A: It is not recommended to drive your 2007 Scion xB with P0304 (Cylinder 4 Misfire Detected) as it can lead to further damage and potentially unsafe driving conditions. It is best to address the issue promptly.

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

A: The cost to repair P0304 in a 2007 Scion xB can vary depending on the exact cause of the misfire and the cost of parts and labor. Repairs may range from a few hundred dollars to over a thousand dollars.

8. Can bad fuel quality cause OBDII code P0304 in a 2007 Scion xB?

A: Poor quality fuel with contaminants or a lower octane rating than recommended can potentially contribute to misfires and trigger OBDII code P0304 in a 2007 Scion xB.

9. Will resetting the OBDII code P0304 in my 2007 Scion xB make the issue go away?

A: Resetting the OBDII code P0304 in a 2007 Scion xB may temporarily turn off the check engine light, but it will not fix the underlying issue causing the cylinder 4 misfire. The problem should be properly diagnosed and repaired.

10. How often should I replace spark plugs in my 2007 Scion xB to prevent OBDII code P0304?

A: It is recommended to replace spark plugs in a 2007 Scion xB according to the manufacturer's recommended maintenance schedule, typically every 30,000 to 100,000 miles depending on the type of spark plugs used. Regular maintenance can help prevent issues like OBDII code P0304.