AutoCodes – Scion – P0303 2007 Scion xB

P0303 2007 Scion xB Code - Cylinder 3 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: P0303 2007 Scion xB indicates Cylinder 3 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 3,302

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 P0303 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 P0303 2007 Scion xB - Cylinder 3 Misfire Detected - AutoCodes.com — P0303 2007 Scion xB Code - Cylinder 3 Misfire Detected

What does this mean?

What are the Possible Causes of the DTC P0303 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 P0303 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 P0303 code means that the cylinder 3 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 3. 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 P0303 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 P0303 2007 Scion xB Code

1. What are the common symptoms of OBDII code P0303 (Cylinder 3 Misfire Detected) on a 2007 Scion xB?

- Common symptoms include rough idling, loss of power, engine vibration, and potentially an illuminated check engine light.

2. What are the possible causes of a cylinder 3 misfire in a 2007 Scion xB?

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

3. How can I diagnose the source of the cylinder 3 misfire on my 2007 Scion xB?

- Diagnostic steps may include checking spark plugs, ignition coils, fuel injectors, compression levels, vacuum leaks, and using a code reader to pinpoint the exact cause.

4. What are some repair tips for fixing a cylinder 3 misfire on a 2007 Scion xB?

- Repair tips may involve replacing spark plugs, ignition coils, fuel injectors, addressing vacuum leaks, performing a compression test, or updating the engine's software.

5. Can driving with a cylinder 3 misfire damage my 2007 Scion xB?

- Continuing to drive with a misfire can potentially cause damage to the catalytic converter, oxygen sensors, or other engine components, so it's best to address the issue promptly.

6. How much does it typically cost to repair a cylinder 3 misfire on a 2007 Scion xB?

- The cost of repair can vary depending on the specific cause of the misfire, but it may range from a few hundred dollars for simple fixes to over a thousand dollars for more complex issues.

7. Is it safe to continue driving my 2007 Scion xB with a cylinder 3 misfire?

- It is not recommended to drive with a misfire as it can lead to further damage and potentially compromise the vehicle's performance and fuel efficiency.

8. Can a cylinder 3 misfire be a recurring problem in a 2007 Scion xB?

- If the root cause of the misfire is not properly addressed, it can become a recurring issue, so it's important to diagnose and fix the problem thoroughly.

9. How long does it typically take to repair a cylinder 3 misfire on a 2007 Scion xB?

- The repair time can vary depending on the specific cause of the misfire and the availability of parts, but it may take a few hours to a full day to diagnose and fix the issue.

10. Will resetting the check engine light resolve the cylinder 3 misfire in my 2007 Scion xB?

- Simply resetting the check engine light will not fix the underlying issue causing the misfire, so it's essential to diagnose and repair the problem to prevent it from reoccurring.