Faulty or fouled spark plug on cylinder 8, especially if the plug is original or has exceeded its service interval; Worn or cracked ignition coil on cylinder 8 that breaks down under the higher load of cold starting; Leaking or clogged fuel injector on cylinder 8 causing an incorrect air-fuel mixture during cranking; Intake manifold gasket leak near cylinder 8 allowing unmetered air into that runner during cold start; Low compression on cylinder 8 from worn piston rings, valve seat issues, or a sticking valve; Carbon buildup on the intake valves of cylinder 8, common on direct-injection BMW engines; Engine control module software or adaptation values that need updating or resetting for cold-start fueling

DTC codes / BMW codes / P1356

P1356 · BMWMisfire During Start Cylinder 8

Q: What does code P1356 mean?

Misfire During Start Cylinder 8. P1356 on a BMW means the engine control module detected a misfire specifically on cylinder 8 during the engine start phase, before the engine reaches normal operating speed. The computer monitors crankshaft speed fluctuations during cranking and flags this code when cylinder 8 fails to contribute its expected power pulse at startup.

P1356 on a BMW means the engine control module detected a misfire specifically on cylinder 8 during the engine start phase, before the engine reaches normal operating speed. The computer monitors crankshaft speed fluctuations during cranking and flags this code when cylinder 8 fails to contribute its expected power pulse at startup.

SystemPowertrain

Code typeBMW specific

SeverityMedium

Fix difficultyIntermediate

AreaIgnition system and misfire

Symptoms you may notice

Rough or stumbling idle immediately after cold start, often smoothing out once the engine warms up
Extended cranking time before the engine fires, especially on cold mornings
A noticeable shake or vibration from the engine bay during the first few seconds of running
Often no symptoms besides the warning light, particularly if the misfire only occurs during the brief start window
Occasional hesitation or stumble when accelerating from a stop after a cold start
A flashing check engine light in severe cases where the misfire persists beyond startup

Common causes, most likely first

Faulty or fouled spark plug on cylinder 8, especially if the plug is original or has exceeded its service interval
Worn or cracked ignition coil on cylinder 8 that breaks down under the higher load of cold starting
Leaking or clogged fuel injector on cylinder 8 causing an incorrect air-fuel mixture during cranking
Intake manifold gasket leak near cylinder 8 allowing unmetered air into that runner during cold start
Low compression on cylinder 8 from worn piston rings, valve seat issues, or a sticking valve
Carbon buildup on the intake valves of cylinder 8, common on direct-injection BMW engines
Engine control module software or adaptation values that need updating or resetting for cold-start fueling

How to diagnose and fix it

Scan all modules for stored and pending fault codes, then check freeze-frame data to confirm the misfire occurred only during the start phase
Inspect the spark plug on cylinder 8 for fouling, incorrect gap, or wear, and replace it if it does not match the specified condition
Swap the ignition coil from cylinder 8 with a known-good coil from another cylinder and recheck for the code to see if the misfire follows the coil
Perform a fuel injector balance test or swap injectors between cylinders to determine if a leaking or clogged injector is the cause
Run a compression test and, if compression is low, follow up with a cylinder leak-down test to isolate valve or ring problems
Smoke-test the intake manifold and vacuum lines for leaks near cylinder 8, paying close attention to the intake gasket
Check for BMW technical service bulletins or software updates related to cold-start misfire and reflash the engine control module if applicable

Cold-start misfire traps on BMW V8s

A P1356 that only appears on cold starts and clears once the engine warms up often points to carbon buildup on the intake valves rather than a failed ignition component, especially on direct-injection engines.
Technicians sometimes replace all eight coils and plugs only to find the misfire returns because a slightly leaking injector on cylinder 8 is washing the plug during cranking.
The code can be set by a weak battery or slow cranking speed that drops crankshaft signal quality, so always verify battery health and starter performance before condemning engine internals.
BMW's misfire detection during start is sensitive to engine coolant temperature sensor readings, and a skewed sensor can cause the control module to deliver the wrong cold-start fuel mixture to cylinder 8.
A P1356 stored alongside lean-bank codes often means an intake leak is affecting cylinder 8 more than others because of its position at the rear of the manifold where gaskets tend to fail first.

Can I keep driving with P1356?

You can usually drive the car if the misfire only occurs briefly at startup and the check engine light is steady, but avoid hard acceleration and long trips until the cause is found. If the light flashes or the engine runs rough continuously, stop driving and have the vehicle diagnosed to prevent catalytic converter damage.

Tools that help

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Guidance is general and written for BMW vehicles. Exact tests and values vary by model, so confirm the fault before replacing parts.