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P1345

Misfire Cylinder 2 With Fuel Cut-off.

  • BMW
  • Powertrain
  • Manufacturer code
  • High severity

How this code is built

P
SystemPowertrain
1
Defined byThe manufacturer
3
AreaIgnition system or misfire
45
FaultThe specific fault in that area

What it means

On BMW, P1345 means the engine control unit has detected misfires on cylinder 2 serious enough that it has cut the fuel supply to that cylinder to protect the catalytic converter. The control unit saw crankshaft speed irregularities attributed to cylinder 2 that exceeded its misfire threshold. The exact trigger limits and the underlying cause vary by engine and model.

Symptoms

  • Engine running rough or shaking, especially at idle
  • Noticeable loss of power and hesitation under acceleration
  • Engine warning light on, possibly flashing under load
  • Fuel smell from the exhaust or raised fuel consumption
  • Difficult or uneven starting
  • Engine running on fewer cylinders with a pulsing exhaust note

Possible causes

  • Worn or faulty spark plug on cylinder 2likely
  • Failed ignition coil on cylinder 2 or its wiring and connectorlikely
  • Faulty or leaking fuel injector on cylinder 2, or its wiringpossible
  • Vacuum or intake air leak affecting cylinder 2, such as a cracked intake boot or sealpossible
  • Low compression on cylinder 2, such as a burnt valve or worn ringsrare
  • Poor fuel quality or low fuel pressure causing lean or irregular combustionrare

How to diagnose

  1. Read all stored and pending codes and note the freeze frame data (load, rpm, temperature) to see when the misfire occurred
  2. Check for other misfire or fuel trim codes, and look at live misfire counters to confirm cylinder 2 is the one affected
  3. Inspect the cylinder 2 coil connector, wiring and spark plug for damage, oil, moisture or heavy wear
  4. Swap the cylinder 2 coil with a neighbouring cylinder, clear the codes and see whether the misfire follows the coil
  5. Check the spark plug condition and gap against the engine's specification, and replace if worn
  6. Test the cylinder 2 injector's electrical supply and resistance, and listen for operation, following the procedure for that engine
  7. Smoke test or inspect the intake system for air leaks near cylinder 2
  8. Carry out a compression or leak-down test on cylinder 2 if ignition and fuel faults are ruled out

How to fix

  • Replace the spark plugs, as a set where the service schedule calls for it
  • Replace the faulty ignition coil on cylinder 2
  • Repair or replace damaged wiring or connectors to the coil or injector
  • Replace or professionally clean and test the faulty injector, as advised for the engine
  • Repair any intake or vacuum leaks by replacing the damaged hose, boot or seal
  • Repair the engine mechanically if compression is low, such as cylinder head or valve work

Can I keep driving?

High severity

Avoid driving where possible, as continued misfiring can overheat and damage the catalytic converter. If you must move the car, keep the load light and the distance short, and get it repaired promptly.

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

This code for other makes

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