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P0303 Ford Code - Cylinder 3 Misfire Detected

Quick Answer

The P0303 diagnostic trouble code indicates that a misfire has been detected in cylinder 3 of the engine. Common causes include Faulty spark plug in cylinder 3, Failed ignition coil in cylinder 3, Clogged fuel injector in cylinder 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 Ford indicates Cylinder 3 Misfire Detected.
Common causes
Common causes include Faulty spark plug in cylinder 3, Failed ignition coil in cylinder 3, Clogged fuel injector in cylinder 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.
What is this?
Table of contents Created and updated by William Orellana on Sep 06, 2024
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Code P0303 Ford Description

The P0303 diagnostic trouble code indicates that a misfire has been detected in cylinder 3 of the engine. This means that the fuel-air mixture in that specific cylinder is not igniting properly, resulting in a loss of power, rough idle, and potential damage to the catalytic converter. Misfires can be caused by a variety of issues, including problems with the ignition system, fuel system, or engine mechanical components.

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

Common Causes of P0303 Ford

  1. Faulty spark plug in cylinder 3
  2. Failed ignition coil in cylinder 3
  3. Clogged fuel injector in cylinder 3
  4. Vacuum leaks affecting cylinder 3
  5. Low compression in cylinder 3

Symptoms of P0303 Ford

  1. Loss of power or acceleration
  2. Rough idle or vibrations
  3. Engine hesitation or stumbling
  4. Increased fuel consumption
  5. Illumination of the check engine light

How to Fix P0303 Ford

  1. Diagnose the specific cause of the misfire (spark plug, ignition coil, fuel injector, etc.)
  2. Replace the faulty component in cylinder 3
  3. Clear the diagnostic trouble codes from the vehicle's computer
  4. Test drive the vehicle to ensure the issue has been resolved
  5. Perform a follow-up inspection to confirm the repair was successful

Cost to Fix P0303 Ford

The cost of repairing a cylinder 3 misfire can vary depending on the specific cause of the issue and the cost of parts and labor in your area. On average, you can expect to pay anywhere from $100 to $300 for parts and labor. Keep in mind that diagnostic time and labor rates can vary, so it's best to get quotes from local repair shops for a more accurate estimate.

What does this mean?

Tech Notes for P0303 Ford

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.

There is a Factory Service Bulletin for the 2011 Ford Mustang:
2011 Ford Mustang Factory Service Bulletin OBDII Code P0303
The Factory Service Bulletin recommends reprogramming the Powertrain Control Module (PCM) to resolve the problem.





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Information for Specific Ford 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 Ford Code

1. What are common symptoms of OBDII code P0303 (Ford) - Cylinder 3 Misfire Detected?

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

2. What are the possible causes of OBDII code P0303 (Ford) - Cylinder 3 Misfire Detected?

- Possible causes include faulty spark plug, ignition coil, fuel injector, vacuum leak, low compression, or issues with the engine control module.

3. How can I diagnose the cause of OBDII code P0303 (Ford) - Cylinder 3 Misfire Detected?

- To diagnose, you can perform a visual inspection, check spark plugs and ignition coils, conduct a compression test, inspect fuel injectors, and use a scan tool to monitor live data.

4. Can driving with OBDII code P0303 (Ford) - Cylinder 3 Misfire Detected cause further damage?

- Continuing to drive with a misfire can potentially cause damage to the catalytic converter, oxygen sensor, or other engine components over time.

5. How do I repair OBDII code P0303 (Ford) - Cylinder 3 Misfire Detected?

- Repair options include replacing the spark plug, ignition coil, fuel injector, addressing vacuum leaks, performing a compression test, or reprogramming the engine control module.

6. Are there any quick fixes for OBDII code P0303 (Ford) - Cylinder 3 Misfire Detected?

- Quick fixes include checking and replacing spark plugs, ensuring proper fuel quality, and addressing any visible vacuum leaks.

7. Can a dirty air filter trigger OBDII code P0303 (Ford) - Cylinder 3 Misfire Detected?

- While a dirty air filter may not directly trigger the code, it can affect engine performance and potentially contribute to a misfire condition.

8. How often should I perform maintenance to prevent OBDII code P0303 (Ford) - Cylinder 3 Misfire Detected?

- Regular maintenance, such as changing spark plugs, inspecting ignition components, and monitoring engine performance, can help prevent misfire issues.

9. Is it safe to continue driving my vehicle with OBDII code P0303 (Ford) - Cylinder 3 Misfire Detected?

- It is generally not recommended to drive with a misfire as it can lead to further damage and potential safety hazards. It is best to address the issue promptly.

10. Can extreme weather conditions trigger OBDII code P0303 (Ford) - Cylinder 3 Misfire Detected?

- Extreme weather conditions, such as very cold temperatures affecting fuel combustion, can potentially contribute to a misfire and trigger the code.

Discuss the causes and fixes for P0303 Ford OBDII Code

Submit a New Comment

  • How do you check for intake leaks on a 2013 Ford Mustang GT 5.0? Also, how do you check if the Fuel injector 3 harness is open or shorted? Thank you!

    Reply to Comment

  • You can check for intake leaks by spraying carburetor cleaner all along the intake to cylinder head, then around the fuel injectors, vacuum lines, throttle body to intake, etc. When you hit the spot where the vacuum leak is the idle will smooth out.
    You can check is the fuel injector harness is open or shorted by checking if the injector is getting the proper voltage from the control unit.

    Reply to Comment

  • Have a 1997 Ford Mustang misfiring 3rd cylinder. Changed plugs and wires. New mass air flow sensor new coil new o2 sensor new fuel pressure regulator new fuel pump new EGR Valve new fuel filter but low fuel pressure. Running out of ideas! Need help!

    Reply to Comment

  • If the problem is consistent, then the next step is to perform a compression test, before replacing any more parts.

    Reply to Comment

  • My check engine light began to blink and my engine was hesitating and there was a loss of power when stepping on the gas the diagnosis revealed that the third cylinder was misfiring codeP0303.

    Reply to Comment

  • What model and year is your Ford? The spark plugs or ignition coil are probably the most common causes of the P0303 code.

    Reply to Comment

  • 2011 Ford Mustang 3.7L V6...... Since I am well acquainted with Murphy and his laws....I spun a crank bearing. The simplest solution was to replace the engine. After replacement, my engine light stays on and will sometimes blink. When it is blinking, I am experiencing a misfire in cylinders 3 and 4. P0303 & P0304. Auto shop that installed the engine confirmed this They have installed all new plugs, and replaced the coils and boots for those cylinders. The intake manifold gasket was also replaced. I am still experiencing the same issues. What's next? Would an ECU reset address this?

    Reply to Comment

  • My next step intake plenum gasket, but some may say the next step is to replace the fuel injector. If possible, try performing a compression test before replacing any more parts.

    Reply to Comment

  • 2017 Ford Edge. Previous P0303 code. Replaced all four plugs and ignition coil. Ran well for a few weeks and the engine light is on again. )Note, I just had my standard oil change and inspection two days ago and everything passed.) Ran the diagnostic code and it is P0303 again. Suggestions?

    Reply to Comment

  • Besides the engine light, do you have any other symptoms? did you cleared the code after replacing the spark plugs and coils?

    Reply to Comment