AutoCodes – BMW – P0306 BMW

P0306 BMW Code - Misfire Cylinder 6

Quick Answer

When a misfire occurs, engine speed will fluctuate. Common causes include Faulty spark plug 6, Clogged or faulty fuel injector 6, Faulty ignition coil 6. 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: P0306 BMW indicates Misfire Cylinder 6 .
Common causes: Common causes include Faulty spark plug 6, Clogged or faulty fuel injector 6, Faulty ignition coil 6.
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 61,259

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 P0306 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 P0306 BMW - Misfire Cylinder 6 - AutoCodes.com — P0306 BMW Code - Misfire Cylinder 6

What does this mean?

What are the Possible Causes of the DTC P0306 BMW?

Faulty spark plug 6
Clogged or faulty fuel injector 6
Faulty ignition coil 6
Fuel injector 6 harness is open or shorted
Fuel injector 6 circuit poor electrical connection
Ignition coil 6 harness is open or shorted
Ignition coil 6 circuit poor electrical connection
Insufficient cylinder 6 compression
Incorrect fuel pressure
Intake air leak

How to Fix the DTC P0306 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 P0306 code means that the cylinder 6 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 6. 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 P0306 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 P0306 BMW Code

1. What are common symptoms of OBDII code P0306 in a BMW indicating a misfire in cylinder 6?

- Common symptoms include engine hesitation, rough idle, loss of power, and potentially increased fuel consumption or emissions.

2. What are some possible causes of a misfire in cylinder 6 triggering OBDII code P0306 in a BMW?

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

3. How can I diagnose the source of the misfire in cylinder 6 if OBDII code P0306 appears in my BMW?

- Diagnostic steps may include inspecting and testing spark plugs, ignition coils, fuel injectors, performing a compression test, checking for vacuum leaks, and scanning the ECU for related faults.

4. Can driving with OBDII code P0306 present in a BMW cause further damage to the engine?

- Continuing to drive with a misfire in cylinder 6 can potentially lead to damage to the catalytic converter, increased emissions, and reduced fuel efficiency over time.

5. How should I address OBDII code P0306 related to a misfire in cylinder 6 in my BMW?

- It is recommended to address the issue promptly by diagnosing and repairing the underlying cause to prevent further damage and ensure optimal engine performance.

6. Are there any DIY repair tips for resolving OBDII code P0306 in a BMW with a misfire in cylinder 6?

- DIY repair tips may include checking and replacing spark plugs, swapping ignition coils between cylinders to test for issues, and inspecting for visible signs of damage or wear.

7. Is it necessary to reset the OBDII code P0306 after resolving the misfire issue in cylinder 6 in a BMW?

- It is recommended to clear the code using an OBDII scanner after addressing the underlying cause to reset the Check Engine Light and monitor for any reoccurrence of the issue.

8. How much can I expect to pay for professional repair of OBDII code P0306 related to a misfire in cylinder 6 in a BMW?

- Repair costs can vary depending on the underlying cause, but expenses may include parts replacement, diagnostic fees, and labor, potentially ranging from a few hundred to over a thousand dollars.

9. Can weather or environmental factors contribute to the occurrence of OBDII code P0306 in a BMW with a misfire in cylinder 6?

- Extreme temperatures, humidity, or driving in dusty conditions can potentially exacerbate issues leading to a misfire in cylinder 6, triggering OBDII code P0306.

10. Does regular maintenance play a role in preventing OBDII code P0306 related to a misfire in cylinder 6 in a BMW?

- Yes, regular maintenance such as timely spark plug replacements, fuel system cleaning, and overall engine health checks can help prevent issues leading to misfires and OBDII codes like P0306.

Discuss the causes and fixes for P0306 BMW OBDII Code

Submit a New Comment

Floyd Mangrum
Date: July 26, 2018 at 6:57 pm

I have a po306 po303 po303 coming up on the code

Reply to Comment
OBDIITech
Date: July 27, 2018 at 5:22 am

What model and year is your BMW? Yuo probably have to start by using high octane gas and/or changing the spark plugs.

Reply to Comment
Jay
Date: May 10, 2025 at 6:17 pm

I have a P0306F code appearing on my 4-cylinder Mini Cooper. Do you know how that is possible since there is not a 6 cylinder? It has confused me to no end honestly. Thanks

Reply to Comment
- OBDIITech
  Date: May 10, 2025 at 7:17 pm
  Hi, good question. You're right — a 4-cylinder Mini Cooper shouldn't have a P0306 code, since that's a misfire on cylinder 6, and you only have cylinders 1–4.
  
  A few possibilities:
  - The code might not actually be P0306, but something that looks similar. Some scan tools can add extra letters or numbers that confuse things (like P0306F). It could be a manufacturer-specific code related to misfires, but not exactly cylinder 6.
  - Scan tool mismatch: Some cheaper or generic scanners don’t fully communicate with BMW/Mini ECUs and can mislabel the codes.
  - Software issue: Occasionally, a glitch in the ECU or an aftermarket tune can cause weird codes to show up.
  Here’s what I recommend:
  - Rescan the car using a good quality scanner, preferably one that can read BMW/Mini-specific codes (like Autologic, Foxwell NT510 Elite, or ISTA).
  - Pay attention if there are any regular P0300 codes (random/multiple misfires) or cylinder-specific misfire codes like P0301–P0304.
  - If the engine runs rough, even without a clear code, still treat it like a misfire on one of the four cylinders — check plugs, coils, and injectors.
  Let me know what else comes up when you rescan, and we can narrow it down from there.
  Reply to Comment