Engine-Codes - Toyota - P0304 2003 Toyota Highlander

P0304 2003 Toyota Highlander Code - Cylinder 4 Misfire Detected

- Code Popularity: 5,963 Views
- Repair Importance Level: 3/3
- Repair Difficulty Level: 3/3
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What are the Possible Causes of the DTC P0304 2003 Toyota Highlander?

NOTE: The causes shown may not be a complete list of all potential problems, and it is possible that there may be other causes.
  • 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

Code Tech Notes

The P0304 code means that the 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 needs to be done to diagnose problem, see "Possible Causes"

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How to Fix the DTC P0304 2003 Toyota Highlander?

Check 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 pins.

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What is the Cost to Diagnose the Code?

Labor: 1.0

The cost to diagnose the P0304 2003 Toyota Highlander code is 1.0 hour of labor. The diagnosis time and labor rates at auto repair shops vary depending on the location, make and model of the vehicle, and even the engine type. Most auto repair shops charge between $75 and $150 per hour.

When is the Code Detected?

Engine Cylinder 4 is Misfiring.

What are Code Possible Symptoms?

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

What Does the P0304 2003 Toyota Highlander Code Mean?

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.

P0304 2003 Toyota Highlander Code - Cylinder 4 Misfire Detected

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