Engine-Codes - Buick - P0304 Buick

P0304 Buick Code - Cylinder 4 Misfire Detected

- Code Popularity: 25,399 Views
- Repair Importance Level: 3/3
- Repair Difficulty Level: 3/3
Table of contents

|What are the Possible Causes of the Code P0304 Buick?

  • Faulty spark plug 4
  • Clogged or faulty fuel injector 4
  • Faulty ignition coil 4
  • Fuel injector 4 harness is open or shorted
  • Fuel injector 4 circuit poor electrical connection
  • Ignition coil 4 harness is open or shorted
  • Ignition coil 4 circuit poor electrical connection
  • Insufficient cylinder 4 compression
  • Incorrect fuel pressure
  • Intake air leak

|How to Fix the P0304 Buick Code?

Start by checking the "Possible Causes" listed above. Visually inspect the related wiring harness and connectors. Check for damaged components and look for broken, bent, pushed out, or corroded connector's pins.

|Code P0304 Buick Tech Notes

The P0304 code means that cylinder 4 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 4. 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 Buick Models:
2000-2020 Buick Factory Service Bulletin OBDII Code P0304
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.

|What is the Cost to Diagnose the Code P0304 Buick?

Labor: 1.0

The cost to diagnose the P0304 Buick code is 1.0 hour of labor. The auto repair's diagnosis time and labor rates vary by location, vehicle's make and model, and even your engine type. Most auto repair shops charge between $75 and $150 per hour.

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|What are Code P0304 Buick Possible Symptoms?

  • Engine Light ON (or Service Engine Soon Warning Light)
  • Lack/loss of power
  • Hard start
  • Engine hesitation

|What Does the P0304 Buick Code Mean?

A misfiring cylinder causes slight variations in the rotational speed of the crankshaft. The Engine Control Module (ECM) can detect these variations by closely monitoring the crankshaft position sensor signal. The signals of the camshaft position sensors are used to determine which cylinder is misfiring. If the ECM detects a misfire rate sufficient to cause emission levels to exceed mandated standards, the Diagnostic Trouble Code (DTC) will be set. Under certain driving conditions, a misfire rate can be high enough to cause the catalytic converter to overheat, damaging the converter. The Malfunction Indicator Lamp (MIL) flashes when the converter is overheating, damaging conditions are present, and the DTC is set. The DTC will be set when the ECM detects a crankshaft rotation speed variation indicating a single-cylinder misfire rate sufficient to cause emissions levels to exceed mandated standards.

P0304 Buick Code - Cylinder 4 Misfire Detected

|Need more Information on the P0304 Buick Code?

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|Need Help with the P0304 Buick Code?

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