P0314

Code

Generic P — Powertrain

Single Cylinder Misfire (Cylinder not Specified)

Brand: Generic

Type: P — Powertrain

Views: UK: 27 EN: 51 RU: 33

AI status

Completed

ready

Completed 100%

Page language: EN

Causes

Faulty spark plug
Faulty ignition coil or ignition module
Fuel injector failure or blockage
Low fuel pressure or weak pump
Mechanical problems (low compression, valve issues, head gasket leak)
Wiring or connector fault to coil/injector

Symptoms

Check Engine Light (MIL) illuminated
Engine runs rough or vibrates at idle
Hesitation or stumbling under acceleration
Loss of power and reduced fuel economy
Repeated or intermittent misfire events
Possible increased exhaust emissions or failed emissions test

What to check

Read freeze frame data and stored misfire counters with a scan tool
Confirm MIL on and note any other DTCs (P0300, P0301–P0308, sensors)
Monitor live data: misfire counts per crankshaft revolution, RPM stability, short/long term fuel trims, O2 sensor voltages
Visual inspection of spark plugs, ignition coils, injector connectors and wiring for corrosion, damage or loose connections
Check fuel rail pressure and fuel trim for fuel delivery issues
Perform a wet/dry compression or leak-down test on all cylinders

Signal parameters

Misfire count (per cylinder or overall)
Crankshaft speed variation (delta RPM)
Short-term and long-term fuel trim (STFT/LTFT)
O2 sensor voltage/waveform (upstream)
Fuel rail pressure and injector pulse width
Ignition primary/secondary waveform (coil primary current, secondary spark trace)

Diagnostic algorithm

Verify P0314 is current and capture freeze frame/failure data with a scan tool
Check for related codes (P0300, P0301–P0308, sensor codes) and address any upstream issues first
Perform visual inspection: spark plugs, coils, injector connectors, wiring harnesses, vacuum lines
Use live-data to identify which cylinder shows irregular contribution: monitor misfire counters, RPM fluctuations and fuel trims
Swap ignition coil to another cylinder: if misfire moves, replace coil (or coil pack/module)
Swap fuel injector with another cylinder to determine if injector is faulty
Check fuel pressure and flow against manufacturer specs; replace fuel filter or pump if pressure is low or erratic
Perform compression and/or leak-down tests; if a cylinder is low, investigate mechanical repair (rings, valves, head gasket)
Inspect crank/cam position sensors and timing; correct timing or replace sensors as needed
After repairs, clear codes, test-drive to confirm misfire is resolved and monitor for return of P0314

Likely causes

Ignition coil or spark plug failure on one cylinder
Clogged or stuck fuel injector for one cylinder
Low cylinder compression (worn rings, valve seating, head gasket)
Wiring or connector fault to a single injector or coil
Intermittent fuel pressure drop or clogged fuel filter

Fault status

⚠️ Status

P0314 — Single Cylinder Misfire detected (cylinder not specified). Investigate ignition, fuel, mechanical integrity and related sensors. Further diagnostics required to identify failing cylinder.

🟡 Repair difficulty: Medium

⏱️ Diagnostic time: 0.5 - 3 hours