The engine computer detects misfires in more than one cylinder or randomly and cannot pinpoint one specific cylinder.
High. If the “Check Engine” lamp is flashing, stop as soon as possible. Unburnt fuel can overheat and damage the catalytic converter.
Gasoline engines most often. Ignition, fuel, intake, engine mechanics.
What does P0300 mean
With each ignition in the cylinder, the crankshaft receives a slight push and accelerates. The computer monitors its revolutions through the crankshaft sensor. When a cylinder "misses", the shaft slows down momentarily. If this happens in different cylinders or without a clear pattern, the computer records P0300.
If the misfires are only in one cylinder, a specific code is usually output as well: P0301–P0306, where the last digit is the cylinder number.
Symptoms
- The engine "shakes" or runs erratically, especially at idle
- Loss of power and stuttering when accelerating
- Difficult ignition
- Increased fuel consumption
- Flashing or steady light "Check Engine"
- The smell of fuel from the exhaust
| Can it be driven?
If the light blinks, no. This is a signal of strong interruptions. Drive only to the nearest safe place, because the catalytic converter can fail in a short time.
If it lights up constantly, the car can reach the service center carefully, without load and high revs. Don't delay: the longer you drive with interruptions, the bigger the repair becomes.
Common reasons
Arranged roughly from most common and least expensive to more serious:
- Worn spark plugs or candles with the wrong heat value.
- Faulty coils or cables — pass current, especially in wet weather.
- Vacuum leak — burst hose, intake manifold gasket, PCV system. The mixture becomes lean (often together with P0171 / P0174).
- Fuel problem — low pressure, weak fuel pump, clogged filter, dirty nozzles or poor quality fuel.
- Wrong sensor readings — flow meter (MAF), crankshaft or camshaft sensor.
- Displaced gear — skipped belt or stretched chain (often with P0016).
- Mechanical problem in the engine — low compression from worn segments, burnt or non-sealing valves, burnt head gasket.
How we diagnose it
- We read all the codes and the frozen data - at what rpm, temperature and load the error was recorded.
- We're looking at the cylinder break counter in real time.
- We check candles, coils and cables, exchange coils between cylinders.
- We look for vacuum leaks and check fuel pressure.
- If everything listed is in order — we measure the compression and do a leak test from the cylinders.