P0300 on Mitsubishi
Random/Multiple Cylinder Misfire Detected
P0300 on Mitsubishi vehicles indicates random/multiple cylinder misfire detected. Au7o has documented this code across 2 Mitsubishi models — most commonly on Eclipse, Outlander. P0300 means the engine computer detected misfires occurring randomly or across multiple cylinders rather than in one specific cylinder. A misfire is when a cylinder fails to ignite its fuel-air mixture properly, which the computer senses through small fluctuations in crankshaft speed. Because it's not isolated to one cylinder, the cause is usually something that affects the whole engine — like fuel, air, or ignition system problems — rather than a single coil or plug. Persistent or heavy misfiring wastes fuel, runs rough, and can damage the catalytic converter, which is why a flashing check engine light should be taken seriously. Typical repair costs on Mitsubishi range from $200 to $5,000, depending on the specific model and root cause.
Common Causes of P0300
- •Worn or fouled spark plugs (across cylinders)
- •Vacuum or intake air leak
- •Weak fuel pump, clogged fuel filter, or low fuel pressure
- •Failing ignition coils or worn spark plug wires
- •Dirty or faulty mass airflow (MAF) sensor
- •Clogged or dirty fuel injectors
- •Faulty crankshaft/camshaft position sensor
- •Low compression or EGR/PCV system faults
P0300 on Mitsubishi by Model
Mitsubishi Eclipse(2 issues)
- Timing Belt Tensioner and Water Pump Failure2000-2012
The Eclipse timing belt tensioner hydraulic damper fails, allowing the timing belt to become loose and potentially jump teeth. The water pump, driven by the timing belt, also develops bearing failure and coolant leaks. These failures are particularly common on the 4G64 and 4G69 engines.
- Cam Angle Sensor (CAS) / Optical Distributor Failure - No-Start and Stalling1990-1999
The 4G63 uses a cam angle sensor (an optical sensor mounted in the distributor housing on the exhaust cam) to provide the crank/cam timing signal to the ECU. With age the CAS optical disc, LEDs/phototransistors, and internal bearing wear out and produce erratic or lost signals. On 1G cars the CAS is base-timing adjustable; on 2G it is fixed. Failure is a classic cause of intermittent no-start, hot-soak no-start, and random stalling on these cars, and it can be intermittent enough that tapping the sensor temporarily restores it. It is frequently misdiagnosed. (Note: crankwalk can mimic these symptoms by physically disturbing the CAS drive.)
Mitsubishi Outlander(1 issue)
- 6B31 3.0L V6 Uses a Timing BELT, Not a Chain — Missed Interval Destroys Later Interference Engines2007-2020
A recurring and expensive owner mistake on V6 Outlanders: buyers and even some independent shops assume a modern V6 has a timing chain, so the belt never gets changed. The 6B31 3.0L V6 fitted to the Outlander runs a rubber timing belt with a service interval around 105,000 miles. Worse, the design changed: early 2007-2009 engines used pistons with valve reliefs and are non-interference, so a snapped belt merely stranded the car, while later 6B31s are interference — a broken belt lets the pistons hit open valves and typically bends valves and damages guides. Mitsubishi enthusiast forum threads are full of owners discovering the belt only after it fails, and of 'belt or chain?' confusion threads. The 2.4L four-cylinder in the same body is chain-driven, which is exactly why the confusion persists.
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View P0300 across all makes →Frequently Asked Questions
What does P0300 mean on Mitsubishi?▼
P0300 stands for "Random/Multiple Cylinder Misfire Detected." P0300 means the engine computer detected misfires occurring randomly or across multiple cylinders rather than in one specific cylinder. A misfire is when a cylinder fails to ignite its fuel-air mixture properly, which the computer senses through small fluctuations in crankshaft speed. Because it's not isolated to one cylinder, the cause is usually something that affects the whole engine — like fuel, air, or ignition system problems — rather than a single coil or plug. Persistent or heavy misfiring wastes fuel, runs rough, and can damage the catalytic converter, which is why a flashing check engine light should be taken seriously. On Mitsubishi specifically, this code is documented across 2 models.
What causes P0300 on Mitsubishi vehicles?▼
Common causes on Mitsubishi: Worn or fouled spark plugs (across cylinders), Vacuum or intake air leak, Weak fuel pump, clogged fuel filter, or low fuel pressure, Failing ignition coils or worn spark plug wires, Dirty or faulty mass airflow (MAF) sensor. Specific causes vary by model and year — see the per-model sections below.
How much does it cost to fix P0300 on a Mitsubishi?▼
Repair costs on Mitsubishi range from $200 to $5,000, depending on the specific model and root cause.
Which Mitsubishi models have P0300 documented?▼
Au7o has documented P0300 on 2 Mitsubishi models: Eclipse, Outlander.