#misfire
15 posts in Car Diagnostics blog about "misfire" — OBD-II diagnostics, DTC codes, repair. ← All posts
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P2146 to P2149: injector group supply voltage circuit
Injectors are fed in groups. A supply fault takes out several cylinders at once, which looks like a catastrophic engine problem and usually is not.
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Vibration at idle: mounts, misfire or a dirty throttle body
A car that shakes at a standstill and smooths out when moving has a short list of causes, and one live-data reading tells you which.
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P0301-P0304: misfire on a specific cylinder and how to localise it
A cylinder-specific misfire code hands you the location for free. The swap test then tells you whether the fault travels with the part or stays with the cylinder.
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P0305 to P0308: misfire on cylinders 5 to 8 and V-engine numbering
The diagnosis is the same as any misfire. What is different is finding the cylinder, because on a V-engine the numbering is rarely what you would guess.
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P0313 and P0314: misfire detected with low fuel level
This is a code with a built-in explanation. The engine misfired, and the ECU noted that the tank was nearly empty — so it declined to blame the ignition system.
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P0316: misfire detected on startup — the cold-start-only fault
P0316 only counts misfires in the first seconds after cranking. That narrow window points at a specific short list of causes that a warm-engine test will never reproduce.
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P0351 to P0358: ignition coil primary and secondary circuit by cylinder
These codes name the cylinder, which is more than a misfire code does at first. But the code names a circuit, and the circuit includes more than the coil.
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Ignition coils: the symptoms people mistake for spark plugs
Coils and plugs produce similar symptoms but are tested differently. How swapping separates them, and why coils die in groups.
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Rough when cold, fine when warm: why that happens
A symptom that disappears as the engine warms is a clue, not a triviality. Why a cold start exposes what a warm engine hides.
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Bad fuel: how to recognise it over OBD and tell it apart from a real fault
After a fill-up the car pulls worse and stumbles under load. Is it the fuel or did something break? The data answers unambiguously — through knock correction behaviour, fuel trims, and when the codes appeared.
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Car jerks when accelerating: what the moment of the jerk tells you
A jerk at low RPM, a hesitation on sudden throttle, and a rhythmic surge at steady speed are three different faults. Diagnosis by exactly when it happens, and what a log should show.
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Check Engine flashing vs steady: the difference that decides whether you keep driving
A steady lamp says "book a diagnostic soon". A flashing lamp says "stop now". They are two distinct signals from one indicator, and confusing them costs a catalytic converter.
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P0201–P0206: injector circuit — when the wire is at fault, not the injector
These codes name a specific cylinder, which is why they get read as "the injector died". In fact the module is complaining about an electrical circuit, and the injector is only one of three elements in it.
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P0300: random / multiple misfire — 12 causes and a step-by-step diagnostic algorithm
Deep dive into P0300: why misfires are "random", how to narrow 12 possible causes to one in 30 minutes, what the AI agent reads from Freeze Frame and Live Monitor.
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Engine Misfire at Idle: 10 Causes, DTC Codes and Diagnostic Order
Misfire symptoms explained: why the engine stumbles at idle and under load, how to identify the problem cylinder, which DTC codes to read first.