OBD-II Diagnostic Trouble Code
P0314 — Single Cylinder Misfire (Cylinder not Specified)
P0314 means the ECM detected misfires that it believes come from one cylinder but could not reliably tell which one. This often happens at higher engine speeds or on rough roads, where crankshaft signal noise makes it hard to assign the misfire to a cylinder.
Severity 4/5
Truck-relevant
Stop within 50 mi
Severity
Stop within 50 mi
Single Cylinder Misfire (Cylinder not Specified)
Code
P0314
Category
Powertrain
Subsystem
Ignition
Truck-relevant
Yes
What this means for truckers
Stop within ~50 miles on a Cummins X15, Detroit DD15, PACCAR MX-13. Driving longer risks damaging adjacent components (turbo housing, head gasket, aftertreatment) and turning a $300 fix into a $3,000 fix.
Before you replace parts — try this first
P0314 on the Ignition system is most often intermittent ignition coil, plug or injector fault on one cylinder — not a dead part. On commercial diesels especially, work these in order before spending money on parts:
- Confirm the symptoms. Match what your truck is doing to the Symptoms section below. If the code is set but the symptoms are not there, clear the code and re-test after a drive cycle — it may not return.
- Clean and dry the sensor connector. Water, road salt, or oil seeping into a connector is the #1 fake sensor failure. Disconnect, look for green corrosion or moisture, spray with electrical contact cleaner, dry, reseat. Many faults clear here for $0.
- Inspect the wiring harness. Trace the wire from the sensor toward the ECM — look for chafing against the engine block, melted insulation near the turbo or exhaust, or pinch points where a clamp has rubbed through.
- Test the sensor before swapping it. Most Common Causes (below) list the expected voltage or resistance range — a $20 multimeter saves a $300 sensor swap that does not fix the problem.
- Only then, replace the part. Use the OEM or a tier-1 aftermarket. Cheap sensors throw the same code in two weeks.
Symptoms
An occasional stumble or miss, usually under load or at higher rpm, with a check-engine light. Many trucks run normally most of the time. If the misfire gets worse you may feel vibration and a loss of power.
Common causes
- CommonIntermittent ignition coil, plug or injector fault on one cylinder ($120–$1400)
- OccasionalCrankshaft position sensor signal noise or a damaged tone ring that hides which cylinder is misfiring ($150–$700)
- OccasionalLoose or corroded coil or injector connector ($80–$350)
- OccasionalDriveline vibration or rough roads being read as misfire when crankshaft variation has not been learned ($0–$250)
How to fix
Watch live per-cylinder misfire counters or run a cylinder contribution test to find the weak cylinder
When to use: First step
Check the crankshaft position sensor signal with a scope and inspect the tone ring
When to use: When no single cylinder stands out
Perform a crankshaft variation relearn if the engine supports it
When to use: After sensor, ECM or flywheel work, or if P0315 is also present
Inspect and replace coils, plugs or injectors on the suspect cylinder
When to use: Once one cylinder is identified
Affects most
No specific vehicle pattern found in our complaint database. This code can appear on any vehicle that supports OBD-II diagnostics.
Related
- → Browse all DTC trouble codes
- → Decode a VIN to check codes for your truck
- → Owner-operator maintenance guides
- → P0300 — Random/Multiple Cylinder Misfire Detected
- → P0301 — Cylinder 1 Misfire Detected
- → P0302 — Cylinder 2 Misfire Detected
- → P0303 — Cylinder 3 Misfire Detected
- → P0304 — Cylinder 4 Misfire Detected
Frequently Asked Questions
Can I drive with code P0314?
Drive with caution. P0314 is severity 4 — stop within ~50 miles. Most commercial diesel codes at this severity (turbo, fuel rail, transmission solenoid) can damage adjacent expensive components if left unrepaired. Get to a service location before highway-speed loads.
How much does it cost to fix P0314 on a commercial truck?
Total repair cost ranges varies depending on the root cause. The cheapest fix is usually the first one listed below — Intermittent ignition coil, plug or injector fault on one cylinder — which is also the most common. On commercial trucks the cost is usually higher than passenger vehicles due to part availability and shop labor rates ($120–185/hour at most truck shops, vs $90–130 at general auto shops). DIY-capable fixes (sensors, hoses, filters) are at the low end; major component replacements (turbo actuator, high-pressure fuel pump, transmission solenoid pack) are at the high end. Always diagnose with a scan tool BEFORE replacing parts — guessing wrong on a $1,500 turbo actuator when the actual issue was a $30 boost hose is a common expensive mistake.
Will P0314 fail a DOT inspection?
P0314 is generally not a direct DOT inspection fail item by itself. Inspectors focus on safety-critical systems (brakes, steering, tires, lights, hours-of-service). However, the check engine light alone can trigger additional inspection scrutiny. Best practice: fix the code and clear it before a planned inspection.
What's the difference between P0314 and related codes?
P0314 is closely related to: P0300 (Random/Multiple Cylinder Misfire Detected), P0301 (Cylinder 1 Misfire Detected), P0302 (Cylinder 2 Misfire Detected), P0303 (Cylinder 3 Misfire Detected). These codes share the same subsystem (ignition) and often appear together. If you see this code, scan for the full code list — fixing the root cause usually clears multiple companion codes at once. If only P0314 is set without the companions, the issue is more isolated.
How do I prevent P0314 from coming back after a repair?
For P0314 (Single Cylinder Misfire (Cylinder not Specified)), prevention centers on the ignition system. Use OEM-spec injectors and spark plugs (gas). Address fuel quality issues immediately — bad fuel kills injectors. Cylinder balance test annually for early warning.