P0300 on a 2013 Jeep Grand Cherokee
P0300 is a generic OBD2 powertrain code for random or multiple cylinder misfire. Unlike P0301 through P0308, it does not point to one specific cylinder, so the cause can be ignition, fuel, air, sensor, or mechanical.
Not your vehicle? See general P0300 info.
Most common causes on the 2013 Jeep Grand Cherokee
Ranked from 799 NHTSA owner complaints filed for this vehicle.
- 1
Faulty Fuel Pump Relay / TIPM Failure
High severityThe fuel pump relay (often part of the TIPM) fails, causing improper power delivery, stalling, or a no-start condition. Look for stalling while driving, difficulty starting, and check if the fuel pump relay recall (V62) has been performed or if the external relay has failed.
Reported in 12 NHTSA complaints - 2
Ignition Coil Failure
Medium severityA faulty ignition coil will fail to provide the spark needed for combustion, leading to a misfire. Confirm by swapping the coil to another cylinder and seeing if the misfire follows.
Common cause - 3
Worn or Faulty Spark Plugs
Low severityWorn spark plugs cannot ignite the air/fuel mixture properly, causing random misfires. Inspect spark plugs for wear, carbon buildup, or incorrect gap.
Common cause - 4
Vacuum Leak
Medium severityUnmetered air entering the intake manifold leans out the air/fuel mixture, causing random misfires across multiple cylinders. Check for cracked vacuum hoses or intake manifold gasket leaks using a smoke machine.
Common cause - 5
Low Fuel Pressure / Failing Fuel Pump
Medium severityInsufficient fuel pressure starves the engine, causing random misfires. Test fuel pressure at the rail to confirm it meets specifications.
Common cause - 6
Faulty Fuel Injectors
Medium severityClogged or failing fuel injectors will not deliver the correct amount of fuel, leading to a misfire. Confirm by performing an injector balance test or checking for injector pulse.
Common cause - 7
Camshaft or Crankshaft Position Sensor Failure
Medium severityThese sensors provide timing data to the PCM; if they fail or send erratic signals, the PCM cannot properly time spark and fuel, causing random misfires. Check for related sensor codes and monitor live data.
Common cause - 8
Internal Engine Wear / Low Compression
High severityWorn piston rings, burnt valves, or a blown head gasket can cause low compression, resulting in a misfire. Perform a compression and leak-down test to confirm.
Common cause
These causes are aggregated from NHTSA owner complaints and general repair knowledge — this is not a diagnosis. P0300 on your car still needs shop confirmation before any repair.
Common symptoms
- Flashing or steady check engine light
- Rough idle
- Shaking under acceleration
- Loss of power
- Fuel smell from exhaust
What to check before replacing parts
Scan for cylinder-specific misfire codes
Look for: A companion P0301–P0308 pins the misfire to one cylinder — start there. P0300 with no cylinder code points at something hitting several at once: fuel pressure, a large vacuum leak, or timing.
Inspect the spark plugs and coils
Look for: Pull the plugs: black/sooty = rich, oily = oil intrusion, white/blistered = lean or overheating, cracked porcelain or an out-of-spec gap = replace. Then swap a coil to another cylinder — if a cylinder-specific code follows the coil, the coil is bad.
Check fuel trims for a vacuum leak
Look for: High positive short- and long-term trims (worst at idle, improving as RPM rises) mean unmetered air is getting in. Smoke-test the intake and listen for hissing.
Verify fuel pressure
Look for: Compare running/cranking pressure to the vehicle spec. Low or dropping pressure starves multiple cylinders and reads as a random misfire — suspect the pump, filter, or regulator.
Compression / leak-down test if ignition and fuel check out
Look for: A cylinder 15%+ below the others, or leak-down hissing from the intake (intake valve), exhaust (exhaust valve), or oil filler (rings), means the misfire is mechanical — not a swap-in part.
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