P0300 on Mitsubishi: How to Diagnose & Fix
Random/Multiple Cylinder Misfire Detected
1 Mitsubishi model · 2 documented issues · 1 critical · $200-$1,200 repair
P0300 on Mitsubishi by model: symptoms, diagnosis and fix
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.)
Common Symptoms
- Intermittent no-start / crank but no spark
- Hot-start failure (won't restart until it cools)
- Random stalling while driving
- Rough running that comes and goes
- Symptoms temporarily clear when the sensor is tapped
How to Fix
Diagnose by checking for spark and injector pulse and verifying the CAS output signal on a scope/meter; a bearing that has play or a signal that cuts out when hot confirms it. Replace the cam angle sensor (or the complete optical distributor assembly). On 1G cars, re-set base ignition timing after replacement. Ensure grounds and the connector are clean, as poor grounds mimic CAS faults.
Sources for this issue (2)
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.
Common Symptoms
- Squealing or chirping from timing cover
- Coolant leak from water pump weep hole
- Engine misfiring or rough running
- Timing belt visibly worn or cracked
How to Fix
Replace the timing belt, tensioner, idler pulleys, and water pump as a complete kit every 60,000 miles. Use only OEM or premium aftermarket timing components. Do not reuse the old hydraulic tensioner.
What you need to fix it
Only diagnosis- and fitment-reviewed repair parts are linked here.
- Gates PowerGrip timing component kit with water pump TCKWP340OEMGates TCKWP340
product page explicitly fits 2008-2012 Eclipse 2.4L four-cylinder and identifies Gates TCKWP340 with water pump.
As an Amazon Associate, we earn from qualifying purchases; other part links may also earn au7o a commission. Confirm fitment by VIN before buying.
Sources for this issue (1)
P0300 code reference
General diagnostic-code context. The code alone does not confirm a cause for your vehicle; use the applicable issue card and its sources.
Frequently asked questions
What does P0300 mean on a 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 it is documented across 1 model: Eclipse.
What are the most common causes of P0300?
The most common causes of P0300 are: 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. The specific cause varies by vehicle.
How much does it cost to fix P0300 on a Mitsubishi?
Published repair estimates on Mitsubishi range from $200 to $1,200 depending on the model and root cause. If an issue mentions a recall or campaign, check your VIN with the manufacturer or NHTSA and confirm eligibility and coverage with a dealer.
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Content compiled with AI assistance using NHTSA complaints, TSBs, and owner reports. May contain errors. Always verify with your vehicle's service manual.