Easy one-page printout for the garage or repair shop
This summary uses the existing diagnostic information shown in full below.
Your car's engine has a problem with one of its parts called Cylinder 3. It's not working right, and this can make the car shake or not run smoothly.
The engine's computer has detected that Cylinder 3 is not firing properly, which means it's not burning fuel as it should.
P0303 indicates that the powertrain control module (PCM) has detected a misfire in cylinder number 3. This misfire occurs when the air/fuel mixture in the cylinder does not ignite properly, causing a lack of power and increased emissions.
• Rough engine idle
• Decreased fuel efficiency
• Check engine light on
• Faulty spark plug in cylinder 3
• Bad ignition coil
• Fuel injector issues
Cylinder: A chamber in the engine where fuel is burned to produce power.
Misfire: A failure of the air/fuel mixture to ignite properly in the engine.
• Use an OBD-II scanner to confirm the code.
• Inspect the spark plug in cylinder 3 for wear or damage.
• Check the ignition coil for proper operation.
• Replace the spark plug in cylinder 3.
• Replace or repair the ignition coil.
• Clean or replace the fuel injector.
• OBD-II scanner
• Spark plug socket
• Multimeter
$100 - $300
Moderate
• Toyota Camry
• Honda Accord
• Ford F-150
• Regularly replace spark plugs.
• Perform periodic engine tune-ups.
• Use high-quality fuel.
Engine Performance
• Avoid driving the vehicle until repaired.
• Get a professional diagnosis if unsure.
• Keep up with regular maintenance.
Repairs may be covered under powertrain warranty if the vehicle is within the warranty period.
Misfire codes like P0303 are common and have been used in OBD-II systems since their inception in the mid-1990s.
High – A misfire can lead to further engine damage and should be addressed promptly.
Driving with a misfire can be unsafe and may lead to increased emissions, which could violate local emission laws.
• Engine at operating temperature
• Vehicle running at idle
Cylinder 3 is located in the engine block, and its position depends on the engine configuration (inline or V-type).
Q: Can I drive my car with a P0303 code?
A: It's not recommended to drive with a P0303 code as it can cause further damage to the engine.
Q: How serious is a cylinder misfire?
A: A cylinder misfire is serious and can lead to engine damage if not addressed quickly.
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Fitment Required · Vehicle-fitment part
Commonly relevant for misfire, ignition-efficiency, and some drivability-related repairs.
Misfire and ignition-related faults commonly involve spark plugs as part of the repair path.
Check the correct plug type, gap, and engine application for your vehicle.
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Fitment Required · Vehicle-fitment part
Relevant when the fault points toward ignition-coil performance or cylinder-specific ignition issues.
Some ignition faults involve coil performance or cylinder-specific coil problems.
Match the coil to your engine and confirm the failed component before ordering.
View options on AmazonThese parts may be related to this fault category, but a code by itself does not confirm exact fitment or guarantee that replacing a part will solve the problem.