P0314 - Single Cylinder Misfire (Cylinder not Specified)
Last updated:
System
Powertrain (Engine & Gearbox)
Related Fault Codes
Technical Description
OBD-II fault code P0314 is stored when the Engine Control Module (ECM) detects a misfire event but cannot pinpoint the specific cylinder responsible. The ECM monitors crankshaft speed variations via the Crankshaft Position (CKP) sensor. A misfire causes a momentary deceleration in crankshaft rotation. If the misfire is erratic or if the CKP signal lacks the resolution to distinguish between cylinders (often due to sensor noise or mechanical issues), P0314 is triggered. Persistent misfires can lead to catalyst overheating and damage.
Possible Causes
Worn or fouled spark plugs
Failing ignition coil or ignition wires
Fuel delivery issues (low fuel pressure or clogged injectors)
Intake manifold vacuum leak
Faulty Crankshaft Position (CKP) sensor or damaged tone ring
Symptoms
Recommended Solution
- Visual inspection: Check ignition wires and connectors for corrosion or damage. Inspect intake system for vacuum leaks.
- Measurement: Check spark plug condition. Measure ignition coil primary/secondary resistance (typically 0.5-2.0 Ohms primary, 6k-15k Ohms secondary). Verify fuel pressure meets OEM specs (often 45-60 PSI).
- Advanced diagnosis: Use an oscilloscope to verify the CKP sensor signal integrity. Monitor Fuel Trim (STFT/LTFT) values to rule out lean conditions.
- Component replacement: Replace spark plugs if worn. Clear codes and perform a drive cycle test.
Mechanic's Tip
Before replacing expensive components, always double-check wiring and connections. 80% of all sensor faults are actually due to corroded contacts or broken wires.
Do you also have
other fault codes?
See how P0314 connects with your other fault codes. Our advanced analysis tool identifies causal relationships and root causes directly.