Cylinder 4 Misfire Detected
Table of contents
- Possible Causes
- How To Fix
- Tech Notes
- Cost To Diagnose
- When is the code detected
- Possible Symptoms
- Description
P0304 KIA Possible 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
How do I fix code P0304 KIA?
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’s pins.
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 the problem, see “Possible Causes” above.
- There is a Factory Service Bulletin to upgrade the Powertrain Control Module (PCM) of some 2010 Model Year Forte (TD) Sedan and Koup with 2.0L engines manufactured between 3/5/09~3/17/10. This reflash has enhanced VCM (Variable Charge Motion) Actuator logic to improve a rough idle condition at start-up or a MIL ON and stored DTC P0304 set at start-up. To improve customer satisfaction Kia is requesting the completion of this Service Action on all affected 2010 Forte & Forte Koup w/2.0L engine vehicles.
Cost of diagnosing the P0304 KIA code
The cost of diagnosing the P0304 KIA code is 1.0 hour of labor. The auto repair labor rates vary by location, your vehicle’s make and model, and even your engine type. Most auto repairs shops charge between $75 and $150 per hour.
When is the code detected
Engine Cylinder 4 is Misfiring.
Possible Symptoms
- Engine Light ON (or Service Engine Soon Warning Light)
- Lack/loss of power
- Hard start
- Engine hesitation
P0304 KIA 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.