AutoCodes – Toyota – P0303 2004 Toyota Prius

P0303 2004 Toyota Prius Code - Cylinder 3 Misfire Detected

Quick Answer

When a misfire occurs, engine speed will fluctuate. Common causes include Faulty Spark Plug #3, Clogged or faulty Fuel Injector #3, Faulty Ignition Coil #3. 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 2004 Toyota Prius indicates Cylinder 3 Misfire Detected.
Common causes: Common causes include Faulty Spark Plug #3, Clogged or faulty Fuel Injector #3, Faulty Ignition Coil #3.
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 3,576

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 2004 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 P0303 2004 Toyota Prius - Cylinder 3 Misfire Detected - AutoCodes.com — P0303 2004 Toyota Prius Code - Cylinder 3 Misfire Detected

What does this mean?

What are the Possible Causes of the DTC P0303 2004 Toyota Prius?

Faulty Spark Plug #3
Clogged or faulty Fuel Injector #3
Faulty Ignition Coil #3
Fuel Injector #3 harness is open or shorted
Fuel Injector #3 circuit poor electrical connection
Ignition Coil #3 harness is open or shorted
Ignition Coil #3 circuit poor electrical connection
Insufficient cylinder 3 compression
Incorrect fuel pressure
Intake air leak
Valve timing
Mass air flow meter
Engine coolant temperature sensor
ECM

How to Fix the DTC P0303 2004 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 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 2004 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 P0303 2004 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 P0303 2004 Toyota Prius Code

What are the common symptoms of OBDII code P0303 in a 2004 Toyota Prius?

Common symptoms of cylinder 3 misfire detected (P0303) in a 2004 Toyota Prius include rough idling, loss of power, engine hesitation, and potentially increased fuel consumption.

What are the possible causes of OBDII code P0303 in a 2004 Toyota Prius?

Possible causes of code P0303 in a 2004 Toyota Prius include faulty spark plugs, a malfunctioning ignition coil, vacuum leaks, fuel delivery issues, or a problem with the engine's compression.

How can I diagnose the cause of OBDII code P0303 in my 2004 Toyota Prius?

To diagnose the cause of code P0303, you can start by inspecting the spark plugs, ignition coil, and fuel injectors. Checking for vacuum leaks and performing a compression test can also help pinpoint the issue.

Is it safe to drive my 2004 Toyota Prius with OBDII code P0303?

It is not recommended to drive your 2004 Toyota Prius with code P0303 as a misfiring cylinder can lead to potential engine damage. It is best to address the issue promptly to avoid further problems.

What are some repair tips for fixing OBDII code P0303 in a 2004 Toyota Prius?

Repair tips for addressing code P0303 in a 2004 Toyota Prius include replacing the spark plugs, ignition coil, or fuel injector for cylinder 3. Additionally, checking and repairing any vacuum leaks can help resolve the misfire.

Can a dirty air filter cause OBDII code P0303 in a 2004 Toyota Prius?

A dirty air filter may not directly cause code P0303, but it can contribute to an imbalance in the air-fuel mixture, potentially leading to a misfire in cylinder 3. It is recommended to regularly replace the air filter to maintain engine performance.

How much does it typically cost to repair OBDII code P0303 in a 2004 Toyota Prius?

The cost to repair code P0303 in a 2004 Toyota Prius can vary depending on the specific cause of the misfire. On average, you can expect to pay between $100 to $300 for parts and labor, but the total cost may be higher if additional components need replacement.

Is it necessary to reset the OBDII code P0303 after repairing a 2004 Toyota Prius?

After repairing the issue causing code P0303 in a 2004 Toyota Prius, it is recommended to reset the code using an OBDII scanner. This will clear the error code and allow you to monitor if the misfire has been successfully resolved.