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P0303 2018 Toyota RAV4 Code - Cylinder 3 Misfire Detected

Quick Answer

When the engine misfires, high concentrations of Hydrocarbons (HC) enter the exhaust gas. Common causes include Intake air leak, Faulty spark plug #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 2018 Toyota RAV4 indicates Cylinder 3 Misfire Detected.
Common causes
Common causes include Intake air leak, Faulty spark plug #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 658
How popular is this code, among other codes? Low
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Table of contents Created and updated by William Orellana on Aug 25, 2022
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Code P0303 2018 Toyota RAV4 Description

When the engine misfires, high concentrations of Hydrocarbons (HC) enter the exhaust gas. Extremely high hydrocarbon concentration levels can cause an increase in exhaust emission levels. Extremely high concentrations of hydrocarbons can also cause increases in the three-way catalytic converter temperature, which may cause damage to the three-way catalytic converter. To prevent this increase in emissions and to limit the possibility of thermal damage, the Engine Control Module (ECM) monitors the misfire count. When the temperature of the three-way catalytic converter reaches the point of thermal degradation, the ECM blinks the MIL. To monitor misfires, the ECM uses both the camshaft position sensor and the crankshaft position sensor. The camshaft position sensor is used to identify any misfiring cylinders and the crankshaft position 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 count exceeds the threshold levels and could cause emission control system performance deterioration, the ECM illuminates the MIL and stores a Diagnostic Trouble Code (DTC).
OBDII Code P0303 2018 Toyota RAV4 - Cylinder 3 Misfire Detected - AutoCodes.com
P0303 2018 Toyota RAV4 Code - Cylinder 3 Misfire Detected
What does this mean?

What are the Possible Causes of the DTC P0303 2018 Toyota RAV4?

  • Intake air leak
  • Faulty spark plug #3
  • Faulty ignition coil #3
  • Clogged or faulty fuel injector #3
  • Fuel injectors #3 harness is open or shorted
  • Fuel Injectors #3 circuit poor electrical connection
  • Ignition coils #3 harness is open or shorted
  • Ignition coils #3 circuit poor electrical connection
  • Incorrect Fuel pressure
  • Faulty Mass Air Flow (MAF) Sensor
  • Faulty Engine Control Module (ECM)
  • Faulty Engine Coolant Temperature (ECT) Sensor

How to Fix the DTC P0303 2018 Toyota RAV4?

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 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.

What is the Cost to Diagnose the Code?

Labor: 1.0

To diagnose the P0303 2018 Toyota RAV4 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 2018 Toyota RAV4 code?

Need more information on how to fix the P0303 2018 Toyota RAV4 code? Get Access to Factory Service Manuals

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 2018 Toyota RAV4 Code

1. What are the common symptoms of an OBDII code P0303 in a 2018 Toyota RAV4?

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

2. What are the possible causes of a Cylinder 3 Misfire Detected code in a 2018 Toyota RAV4?

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

3. How can I diagnose the Cylinder 3 Misfire Detected code in my 2018 Toyota RAV4?

- Diagnosing the issue may involve inspecting and testing the spark plugs, ignition coils, fuel injectors, and performing a compression test on cylinder 3.

4. Can a dirty or clogged fuel injector cause a P0303 code in a 2018 Toyota RAV4?

- Yes, a dirty or clogged fuel injector can disrupt the fuel delivery to cylinder 3, leading to a misfire and triggering the P0303 code.

5. Is it safe to drive my 2018 Toyota RAV4 with a Cylinder 3 Misfire Detected code?

- It is not recommended to drive the vehicle with a misfire as it can cause further damage to the engine or catalytic converter. Immediate attention is advised.

6. How can I reset the OBDII code P0303 in my 2018 Toyota RAV4 after fixing the issue?

- The code can be cleared using an OBDII scanner or by disconnecting the car's battery for a few minutes to reset the system.

7. Will replacing the spark plugs fix the Cylinder 3 Misfire Detected code in my 2018 Toyota RAV4?

- Replacing the spark plugs is a common repair for misfires and may resolve the issue, but it's recommended to further diagnose the problem if the code persists.

8. Can a vacuum leak cause a P0303 code in a 2018 Toyota RAV4?

- Yes, a vacuum leak can disrupt the air-fuel mixture going into cylinder 3, leading to a misfire and triggering the P0303 code.

9. Should I take my 2018 Toyota RAV4 to a mechanic for a P0303 code diagnosis and repair?

- If you are not experienced with diagnosing and repairing engine misfires, it is advisable to take your vehicle to a qualified mechanic to properly address the issue.

10. How long does it typically take to repair a Cylinder 3 Misfire Detected issue in a 2018 Toyota RAV4?

- The repair time can vary depending on the exact cause of the misfire, but it generally takes a few hours to a day for diagnosis and repair.

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