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AutoCodes – Generic – P0306

P0306 Code - Cylinder 6 Misfire Detected

Quick Answer

The Engine Control Module (ECM) uses information from the crankshaft position sensor and the camshaft position sensor to determine when an engine cylinder misfire is occurring. 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 indicates Cylinder 6 Misfire Detected.
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 92,117
How popular is this code, among other codes? Medium
What is this?
Table of contents Created and updated by William Orellana on Aug 09, 2022
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Code P0306 Description

The Engine Control Module (ECM) uses information from the crankshaft position sensor and the camshaft position sensor to determine when an engine cylinder misfire is occurring. By monitoring variations in the crankshaft rotation speed for each cylinder, the ECM can detect individual cylinder misfire events.
Extreme cylinder misfire events can cause catalytic converter damage. The malfunction indicator lamp (MIL) will flash when the conditions for catalytic converter damage are present. The Diagnostic Trouble Codes (DTC) P0306 correspond to cylinders 6. When the ECM detects that one or more specific cylinders are misfiring, the DTC for the respective misfiring cylinder will set, and up to 2 of the corresponding fuel injectors are disabled for a minimum of 30 s. The ECM will then re-enable the fuel injector and, after approximately 200 engine revolutions, will determine if the misfire is still present. If the misfire is still present, the ECM will disable the fuel injector again repeating the process. If the misfire is not present, the fuel injector will remain enabled by the ECM. In Spark Ignition Direct Injection (SIDI) system applications, if a fuel injector fault DTC is set during a misfire event, the ECM will not re-enable the injector.
OBDII Code P0306 - Cylinder 6 Misfire Detected - AutoCodes.com
P0306 Code - Cylinder 6 Misfire Detected
What does this mean?

What are the Possible Causes of the DTC P0306?

  • 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?

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 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 need to be done to diagnose the problem, see "Possible Causes".

P0014 / P0306 2002 Trailblazer








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What is the Cost to Diagnose the Code?

Labor: 1.0

To diagnose the P0306 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 P0306 code?

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Information for Specific Makes

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 Code

1. What are common symptoms of OBDII code P0306 (Cylinder 6 Misfire Detected)?

Symptoms may include engine misfiring, rough idling, loss of power, decreased fuel efficiency, and potential engine vibrations.

2. What are the possible causes of a Cylinder 6 misfire detected error code?

Common causes may include faulty spark plugs, ignition coils, fuel injectors, vacuum leaks, low compression in the cylinder, or issues with the engine control module.

3. How can I diagnose the source of the Cylinder 6 misfire on my vehicle?

Diagnosis typically involves checking spark plugs, ignition coils, fuel injectors, compression levels, vacuum leaks, and the engine control module using diagnostic tools and a systematic approach.

4. Can a dirty or clogged fuel injector cause a Cylinder 6 misfire?

Yes, a dirty or clogged fuel injector can disrupt the proper fuel flow to Cylinder 6, leading to a misfire and triggering the P0306 error code.

5. Is it safe to continue driving with an OBDII code P0306 (Cylinder 6 Misfire Detected) present?

Continuing to drive with a misfire can potentially cause damage to the catalytic converter or other engine components. It is recommended to address the issue promptly to prevent further damage.

6. How can I repair a Cylinder 6 misfire issue myself?

DIY repair steps may include replacing spark plugs, ignition coils, or fuel injectors, checking for vacuum leaks, performing a compression test, and clearing the error code using an OBDII scanner.

7. Can a bad ignition coil cause a Cylinder 6 misfire?

Yes, a faulty ignition coil can lead to a lack of spark in Cylinder 6, causing a misfire and triggering the P0306 error code.

8. What role does the engine control module (ECM) play in a Cylinder 6 misfire situation?

The ECM monitors engine performance and can identify misfires in specific cylinders, such as Cylinder 6, by analyzing data from sensors. A malfunctioning ECM can also contribute to misfire issues.

9. Are there any preventive maintenance measures to avoid a Cylinder 6 misfire in the future?

Regularly servicing and replacing spark plugs, ignition coils, and fuel injectors, as well as addressing any engine performance issues promptly, can help prevent Cylinder 6 misfires and related error codes.

10. Can extreme weather conditions impact the likelihood of a Cylinder 6 misfire?

Extreme temperatures, humidity, or environmental factors can affect engine performance and potentially lead to misfires, including those in Cylinder 6. Maintaining proper engine health and monitoring for symptoms is crucial in such conditions.

Discuss the causes and fixes for P0306 OBDII Code

Submit a New Comment

  • Engine light on p0306 code. Switch coil replace spark plug replace injecter. Ck ck. Wiring ck. Comprestion all ck ok. Light keep comes on same code??

    Reply to Comment

  • If the plug is wet, you might have a head gasket leaking coolant into the cylinder. Please check your coolant level ASAP.

    Reply to Comment

  • Replaced plugs, wires, rotor, cap, & distributer. Still showing same code! whatsup!

    Reply to Comment

  • What make, model and year is your vehicle? You should perform a compression test, the engine may have a blown head gasket.

    Reply to Comment
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