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P1354

Misfire During Start Cylinder 7.

  • BMW
  • Powertrain
  • Manufacturer code
  • Medium severity

How this code is built

P
SystemPowertrain
1
Defined byThe manufacturer
3
AreaIgnition system or misfire
54
FaultThe specific fault in that area

What it means

On a BMW, P1354 means the engine control unit detected combustion misfires on cylinder 7 while the engine was being started. The unit monitors crankshaft speed fluctuations during cranking and flagged an irregularity attributed to that cylinder. It is only seen on BMW multi-cylinder engines (V8 or V12), and the cylinder numbering depends on the engine.

Symptoms

  • Rough or uneven running straight after a cold or hot start
  • Engine management warning light on
  • Hesitation or shaking when pulling away
  • Smell of unburnt fuel from the exhaust at start-up
  • Extended cranking or slight stumble before the engine settles
  • Possible reduced power if the fault continues

Possible causes

  • Worn or faulty spark plug on cylinder 7likely
  • Failing ignition coil on cylinder 7likely
  • Faulty or leaking fuel injector on cylinder 7possible
  • Damaged wiring or poor connector contact to the coil or injector on cylinder 7possible
  • Vacuum or intake air leak affecting that cylinder, such as a split intake boot or leaking gasketpossible
  • Low compression on cylinder 7 from valve or piston ring wearrare
  • Crankshaft position sensor or reluctor wheel fault giving false misfire detectionrare

How to diagnose

  1. Read all stored codes and freeze frame data, noting engine temperature, speed and load when the fault was set, and check for other misfire or fuel trim codes
  2. Confirm which physical cylinder is cylinder 7 for the specific engine, as numbering varies by model
  3. Inspect the coil, connector and wiring on cylinder 7 for damage, oil contamination or corrosion
  4. Remove the spark plug on cylinder 7 and check its condition and gap against the others
  5. Swap the coil with a neighbouring cylinder, clear the codes and see whether the misfire follows the coil
  6. Check fuel injector operation and resistance on cylinder 7 and look at fuel trims for signs of a lean or rich condition
  7. Smoke test or inspect the intake system for air leaks
  8. Carry out a compression or leak-down test on cylinder 7 if the ignition and fuel side check out

How to fix

  • Replace the spark plugs, ideally as a full set, if worn or fouled
  • Replace the faulty ignition coil on cylinder 7
  • Replace or professionally clean and test the faulty fuel injector
  • Repair damaged wiring or connectors, or replace the affected harness section
  • Repair intake leaks by replacing split hoses, boots or gaskets
  • Carry out the necessary engine repair if the compression test shows mechanical wear

Can I keep driving?

Medium severity

The car can usually be driven short distances to a workshop, but avoid heavy loads and high revs. A persistent misfire can overheat and damage the catalytic converter, so get it checked soon, and stop driving if the warning light flashes.

Guide written by AI from the code's definition. Confirm with a diagnosis before replacing parts.

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