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Engine-Codes – Scion – P0303 Scion

P0303 Scion Code - Cylinder 3 Misfire Detected

Quick Answer

The P0303 code for a Scion indicates that a misfire has been detected in cylinder 3 of the engine. Common causes include Faulty spark plugs, Faulty ignition coils, Clogged fuel injector. 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 Scion indicates Cylinder 3 Misfire Detected.
Common causes
Common causes include Faulty spark plugs, Faulty ignition coils, Clogged fuel injector.
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.
What is this?
Table of contents Created and updated by William Orellana on Sep 07, 2024
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Code P0303 Scion Description

The P0303 code for a Scion indicates that a misfire has been detected in cylinder 3 of the engine. A misfire occurs when the fuel-air mixture in the cylinder fails to ignite at the proper time, leading to a disruption in the combustion process. This can result in a loss of power, rough idling, decreased fuel efficiency, and potentially even engine damage if left unresolved.

OBDII Code P0303 Scion - Cylinder 3 Misfire Detected
P0303 Scion Code - Cylinder 3 Misfire Detected

Common Causes of P0303 Scion

  1. Faulty spark plugs
  2. Faulty ignition coils
  3. Clogged fuel injector
  4. Vacuum leak
  5. Low compression in cylinder 3

Symptoms of P0303 Scion

  1. Rough idling
  2. Loss of power
  3. Engine vibration
  4. Hesitation during acceleration
  5. Check engine light illuminated

How to Fix P0303 Scion

  1. Begin by diagnosing the specific cause of the misfire, such as testing the spark plugs, ignition coils, and fuel injector for proper function.
  2. Replace any faulty components identified during the diagnostic process, such as installing new spark plugs, ignition coils, or fuel injectors.
  3. Check for and repair any vacuum leaks in the intake system.
  4. Perform a compression test on cylinder 3 to ensure that it is within the manufacturer's specified range.
  5. Clear the diagnostic trouble codes from the ECM and test drive the vehicle to ensure that the misfire issue has been resolved.

Cost to Fix P0303 Scion

The cost of repairing a cylinder 3 misfire in a Scion can vary depending on the specific cause of the issue and the cost of parts and labor in your area. Typically, the cost of replacing spark plugs, ignition coils, or a fuel injector can range from $150 to $500. Additional costs may apply if there are other underlying issues that need to be addressed. It is recommended to get a detailed quote from a reputable auto repair shop in your area to get a more accurate estimate.

What does this mean?

Tech Notes for P0303 Scion

The P0303 code means that 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 need to be done to diagnose the problem. See "Possible Causes" for the most common problems.

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Information for Specific Scion Models

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 Scion Code

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  • I had a new heater core put in 2006 scion tc. heater works but now my engine light is on ant reads 303 misfire .....coincidence or can this be caused by shitty mechanic work. a week after replacing HC mt car over heated and heater quit working . they said it was bad radiator cap ? wouldn't they check something like that when dealing with cooling system? frustrated!!!

    Reply to Comment

  • Coincidence, unless the mechanic remove some engine part to replace the heater core, which is unusual, and forgot connected back, then replacing the heater core has nothing to do with the cylinder misfire.

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