P0300 on Lexus
Random/Multiple Cylinder Misfire Detected
P0300 on Lexus vehicles indicates random/multiple cylinder misfire detected. Au7o has documented this code across 3 Lexus models — most commonly on IS, LX, RC. 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 Lexus range from $250 to $20,000, 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 Lexus by Model
Lexus IS(2 issues)
- Carbon Buildup on Intake Valves (2.0T)2016-2022
The direct-injected 2.0L turbo four-cylinder in the IS200t/IS300 accumulates heavy carbon deposits on the intake valves since fuel is not sprayed over the valves to clean them. This leads to rough idle, hesitation under acceleration, and reduced power output typically between 40,000-80,000 miles.
- Valve Cover Gasket Leaks Causing Oil Smell and Misfire Risk2001-2005
Aging valve cover gaskets on the 2JZ-GE commonly harden and leak, allowing oil to seep onto the cylinder head, spark plug tube seals, and exhaust side of the engine. Owners often notice a burnt-oil smell, visible oil around the valve covers, and occasional misfires if oil contaminates ignition components. This is one of the most common age-related engine leaks on the first-gen IS300.
Lexus LX(1 issue)
- V35A-FTS 3.4L Twin-Turbo V6 Main Bearing / Engine Failure Risk Covered by Toyota-Lexus Recall2022-2024
The 2022+ Lexus LX uses the V35A-FTS twin-turbo V6 that is included in Toyota/Lexus campaigns for potential engine damage from machining debris and resulting main-bearing failure. Owners have reported knocking, reduced power, check-engine lights, and in some cases complete engine replacement. This is one of the most serious documented issues for the current LX because it can lead to sudden engine failure and very expensive repairs outside recall coverage.
Lexus RC(1 issue)
- Carbon Buildup on Intake Valves (2.0T)2016-2022
The direct-injected 2.0L turbo in the RC200t and RC300 accumulates carbon deposits on the intake valves identically to the IS with the same engine. Without port injection to wash the valves, carbon buildup causes progressive performance degradation starting around 40,000 miles.
Looking for P0300 on a different make?
View P0300 across all makes →Frequently Asked Questions
What does P0300 mean on Lexus?▼
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 Lexus specifically, this code is documented across 3 models.
What causes P0300 on Lexus vehicles?▼
Common causes on Lexus: 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 Lexus?▼
Repair costs on Lexus range from $250 to $20,000, depending on the specific model and root cause.
Which Lexus models have P0300 documented?▼
Au7o has documented P0300 on 3 Lexus models: IS, LX, RC.