OBD2 Codes

Dodge P0300 – Meaning, Causes, Symptoms, & Fixes

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Dodge Code P0300 Definition

Random/Multiple cylinder misfire detected.

What Does Dodge P0300 Mean?

Dodge code P0300 indicates that one or more cylinders are experiencing misfires. A misfire occurs when an insufficient amount of fuel is burning in a cylinder. The efficient burning of fuel is essential to engine operation as the combustion of fuel is what provides the energy to power the engine in your Dodge. A misfire from one or more cylinders can be caused by many reasons from a faulty ignition system, fuel system or internal engine failure. When P0300 occurs it should be fixed immediately as long term driving with engine misfires could cause consequential damage to the engine in your Dodge.  Many times P0300 occurs when there are worn out spark plugs, spark plug wires, or a faulty ignition coil.

Dodge P0300 Symptoms

  • Check Engine Light is on
  • Check Engine Light flashing
  • Engine runs rough and shaking
  • Lack of power from the engine
  • Fuel smell from the exhaust
  • Hesitations/Jerking when accelerating

Dodge P0300 Causes

(* = Most Common)

  • Faulty or worn spark plugs *
  • Faulty spark plug wires or coils *
  • Distributor failure *
  • Faulty fuel injector *
  • Vacuum leak
  • Low fuel pressure
  • Camshaft sensor defective
  • Crankshaft sensor defective
  • Engine timing off
  • Leaking head gasket
  • Low engine compression
  • Poor quality fuel

Dodge Code P0300 Severity – Severe

 

Dodge code P0300 should be repaired immediately. Ignoring this error could result in ignition failure, catalytic converter damage, and unsafe/dangerous conditions while operating your Dodge.

Dodge Code P0300 Common Diagnosis Mistakes

Loose fitting electrical connectors and broken or disconnected vacuum hoses are often overlooked.

Dodge Code P0300 Diagnosis Steps

Tools Needed to Diagnose:

  • Tools You May Already Have:
  • Tools You May Need (FIXD’s Top Picks From Amazon):
    • FIXD
    • Digital multimeter
    • 5/8in. Spark Plug Socket
    • Ratchet, sockets, and extensions
    • Fuel pressure gauge
    • Compression tester
    • Leakdown tester
    • Spark plugs
    • Spark plug wires

How To Diagnose Dodge Code P0300

  1. Use FIXD to scan your Dodge to verify P0300 is the only code present. If other codes are present, they must be addressed first.
  2. Check for loose connectors at the ignition coils or for damaged wiring. Look for loose engine ground wires as well. These can cause random misfire conditions. Tighten or connect where necessary.
  3. Check the condition of your spark plugs and spark plug wires. Worn and old spark plug wires are common causes of random misfires. Replace spark plugs and wires if needed and recheck for misfires.
  4. If you have determined that your ignition system is operating correctly, there may be a problem within your fuel system that is causing the random misfires. The following should be checked to ensure the engine is getting the proper amount of fuel:
    • Check fuel pressure. Low fuel pressure can cause intermittent misfires on multiple cylinders. When the pressure is below the specification, the engine does not receive the proper amount of fuel and will start to lean misfire. The fuel pump or fuel pressure regulator could be the source of the low fuel pressure.
    • Check that the fuel injectors are functioning properly and activating. Random misfires can be a sign of faulty or clogged fuel injectors that need to be replaced. Also check that the fuel injector wiring is not damaged and is connected properly.
  5. If the ignition system and fuel system checks out you may want to perform an engine compression test and leakdown test to see if there are any mechanical problems causing your misfire. Some common mechanical problems that cause misfire can be:
    • Broken valve spring
    • Broken piston ring
    • Worn valve guides
    • Burned valve
    • Timing chain or belt skipped tooth and engine is off time.

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2 Comments

  1. 2005 Dakota, 4.7L, 6-spd manual – P0300 intermittent, frequent; when it occurs, then, almost immediately after engine start (often following 1st engine start of the day, repeating after engine cools . . . maybe). Code reader verifies, consistently, event occurs, ALWAYS, at less than 400 rpm (nominal engine idle = 750-900 rpm!); never under load or accelerating. Initial indications: rough running, “studdering” engine, resists responding to accelerator pedal, then _smooths out_ when holding engine rpm near 2000 for 30-45 seconds. When anticipating the event, if caught quickly, early, engine may _not_ throw P0300 code. Does not throw code while, otherwise, in normal operations; typically occurs following the transition, prior to start, through start sequence, to normal operation. Whether or not engine throws P0300 code (and even w/ “check engine” light illuminated), after engine start, engine, otherwise, runs perfectly, i.e., idles smooth, runs smooth, responsive, and strong. “Intermittent” characteristic, and unusually low rpm occurrence suggests an electrical/ignition (or some other illusive sensor) issue rather than fuel, or mechanical issues that would likely not “come and go . . . sometimes”, but would be constant/predictable, at all rpm’s, and would likely not “smooth out/disappear” . . . right?

    1. Situation consistent , basic description, in the morning start the engine warms up, goes into a multiple misfire turn engine off wait 15 to 20 seconds start engine runs beautifully runs smooth, strong very responsive, stop go to the store 30 45 minutes return to truck. 4.7 L automatic 2007 Dakota. Start
      engine after 20 30 seconds multiple misfire turn off engine wait 15-20 seconds restart engine runs beautifully, strong, very responsive will give me up to 18 miles to the gallon on the highway. Replaced 4 Oxygen Sensors, Cam Sensor, 8 Ign. Coils, 8 spark plugs, fuel pump, charcoal canister, did run better afterwards, had catalytic converter problem, removed both to check, have not replaced them, turned them into mini mufflers. Has been going on for over a year. Besides having to start Truck let idle for 15 to 20 seconds then restart, Truck runs Great. 84000 miles on Odometer.

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