Engine-CodesCadillac – P0307 Cadillac

P0307 Cadillac Code - Cylinder 7 Misfire Detected

Quick Answer

When a Cadillac vehicle's diagnostic system detects a misfire in cylinder 7, it means that the engine's cylinder 7 is not firing properly, leading to a loss of power, rough idling, decreased fuel efficiency, and potential damage to the catalytic converter. Common causes include Faulty spark plug in cylinder 7, Failing ignition coil in cylinder 7, Clogged or dirty fuel injector in cylinder 7. 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
P0307 Cadillac indicates Cylinder 7 Misfire Detected.
Common causes
Common causes include Faulty spark plug in cylinder 7, Failing ignition coil in cylinder 7, Clogged or dirty fuel injector in cylinder 7.
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.
Table of contents Created and updated by William Orellana on Aug 30, 2024
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Code P0307 Cadillac Description

When a Cadillac vehicle's diagnostic system detects a misfire in cylinder 7, it means that the engine's cylinder 7 is not firing properly, leading to a loss of power, rough idling, decreased fuel efficiency, and potential damage to the catalytic converter. This issue can be caused by a variety of factors, such as ignition system problems, fuel delivery issues, vacuum leaks, or even internal engine mechanical problems. If left unaddressed, a misfire can lead to further engine damage, reduced performance, and increased emissions.

OBDII Code P0307 Cadillac - Cylinder 7 Misfire Detected
P0307 Cadillac Code - Cylinder 7 Misfire Detected

Common Causes of P0307 Cadillac

  1. Faulty spark plug in cylinder 7.
  2. Failing ignition coil in cylinder 7.
  3. Clogged or dirty fuel injector in cylinder 7.
  4. Vacuum leaks in the intake manifold or vacuum hoses.
  5. Low compression in cylinder 7 due to worn piston rings or valves.

Symptoms of P0307 Cadillac

  1. Rough idling or vibrations while the engine is running.
  2. Loss of power or acceleration.
  3. Engine misfires or hesitation during acceleration.
  4. Increased fuel consumption.
  5. Illumination of the Check Engine Light.

How to Fix P0307 Cadillac

  1. Diagnose the specific cause of the misfire in cylinder 7 using a scan tool and inspection of spark plugs, ignition coils, and fuel injectors.
  2. Replace the faulty spark plug in cylinder 7 if it is worn or fouled.
  3. Test and replace the ignition coil in cylinder 7 if it is malfunctioning.
  4. Clean or replace the fuel injector in cylinder 7 if it is clogged or faulty.
  5. Check for vacuum leaks and repair any damaged hoses or gaskets.

Cost to Fix P0307 Cadillac

The cost of repairing a cylinder 7 misfire in a Cadillac can vary depending on the specific cause of the issue and the labor rates in your area. Generally, replacing a spark plug or ignition coil can cost between $50 to $200 per part, while cleaning or replacing a fuel injector can range from $100 to $500. The total repair cost, including parts and labor, can typically range from $150 to $800. It's recommended to consult with a trusted mechanic or dealership for an accurate estimate based on your Cadillac model and location.

Tech Notes for P0307 Cadillac

The P0307 code means that cylinder 7 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 7. If the problem persists more tests need to be done to diagnose the problem, see "Possible Causes".

There is a Factory Service Bulletins for All 2000-2020 Cadillac Models:
2000-2020 Cadillac Factory Service Bulletin OBDII Code P0307
This Factory Service Bulletin explains how this condition may be caused by significant carbon build-up on the intake and/or exhaust valves due to fuel contamination or incomplete burning of the fuel.

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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.

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