AutoCodes – BMW – P0303 BMW

P0303 BMW Code - Misfire Cylinder 3

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 BMW indicates Misfire Cylinder 3 .
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 56,166

How popular is this code, among other codes? Medium

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 BMW 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 BMW - Misfire Cylinder 3 - AutoCodes.com — P0303 BMW Code - Misfire Cylinder 3

What does this mean?

What are the Possible Causes of the DTC P0303 BMW?

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

How to Fix the DTC P0303 BMW?

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 BMW 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.

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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 BMW Code

1. What are common symptoms of OBDII code P0303 (Misfire Cylinder 3) in a BMW?

Common symptoms include engine misfiring, rough idle, loss of power, and potential engine vibrations.

2. What are the possible causes of OBDII code P0303 in a BMW?

Possible causes include faulty ignition coil, spark plug, fuel injector, vacuum leak, low compression, or issues with the engine's air-fuel mixture.

3. How can I diagnose the source of the misfire in Cylinder 3 in my BMW?

You can diagnose the issue by performing a compression test, checking the spark plug and ignition coil for damage, inspecting the fuel injector, and scanning for any additional trouble codes.

4. What should I do if my BMW displays OBDII code P0303?

If your BMW shows code P0303, it is recommended to address the issue promptly to prevent potential damage to the catalytic converter and other engine components.

5. Can I continue driving my BMW with OBDII code P0303 (Misfire Cylinder 3)?

It is not recommended to drive your BMW with a misfire condition, as it can lead to further damage and decrease in fuel efficiency. It's best to address the issue as soon as possible.

6. How can I repair OBDII code P0303 in my BMW?

Repair options may include replacing the faulty ignition coil, spark plug, fuel injector, or addressing any vacuum leaks. It is advisable to consult a professional mechanic for accurate diagnosis and repair.

7. Can a dirty or clogged fuel injector cause OBDII code P0303 in a BMW?

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

8. Why is it important to address OBDII code P0303 promptly in my BMW?

Addressing code P0303 promptly is crucial to prevent potential engine damage, improve overall performance, and maintain fuel efficiency in your BMW.

9. How can regular maintenance help prevent OBDII code P0303 in my BMW?

Regular maintenance, including timely spark plug and ignition coil replacements, fuel system cleaning, and overall engine tune-ups, can help prevent misfire issues like code P0303 in your BMW.

10. Is it necessary to reset the OBDII code P0303 after repairing the issue in my BMW?

Yes, it is recommended to reset the code after repairing the underlying issue to clear the fault code memory and ensure proper monitoring of the engine's performance.