P0314
Single Cylinder Misfire (Cylinder not Specified)
If your vehicle's onboard computer has flagged the diagnostic trouble code P0314, it refers to a detected anomaly regarding "Single Cylinder Misfire (Cylinder not Specified)". This systemic engine fault needs a targeted check before symptoms expand.
Driver's Summary
When your OBD2 scanner shows P0314, the engine control module has flagged an issue specifically related to single cylinder misfire (cylinder not specified). Drivers typically experience intermittent engine shudder, slight power loss, check engine light when this code is active. This is a moderate-severity fault — plan a repair shop visit within the week to keep it from escalating.
Symptoms
Intermittent engine shudder, slight power loss, check engine light
Common Causes
- Crankshaft position sensor variation out of sync
- Intermittent vacuum leak
- Failing spark plug or wire
- Poor fuel quality
How to Fix
- 1 Perform CKP (Crankshaft Position) system variation relearn
- 2 Check for vacuum leaks
- 3 Inspect spark plugs and wires
- 4 Add fuel system cleaner
Technical Explanation
Detection of P0314 occurs when the ECM cross-references multiple sensor inputs and determines that the reported values are physically inconsistent or out-of-range. Misfire rate is counted per cylinder over rolling windows and compared against two thresholds: a catalyst-damaging rate (triggers flashing MIL) and an emissions-exceeding rate (triggers solid MIL). The PCM logs which cylinder is misfiring based on crankshaft position at the time of each detected event. The fault remains stored in memory even after the MIL is cleared; it becomes a confirmed DTC after failing two consecutive drive cycles, and the PCM logs a freeze frame record of the engine's exact operating state at the moment of detection.
Is It Safe to Drive?
Medium-severity fault: the car functions but not optimally. The crankshaft position sensor variation out of sync issue will not resolve itself and will cause measurable long-term wear. A repair in the $50–$250 range now avoids far higher costs later.
Mechanic's Pro Tip
The fastest isolation technique for P0314 is the coil swap test: move the ignition coil from the affected cylinder to a neighboring cylinder and clear the code. If the misfire follows the coil, it's the coil. If it stays on the same cylinder, focus on the spark plug, injector, or compression. Never replace coils without also replacing the spark plug in that cylinder — a fouled plug will kill a new coil within weeks.
CKP Relearn: 50 - 150; Tune-up: 100 - 250