P0314 — Single Cylinder Misfire (Cylinder not Specified)

powertrain (engine/transmission)

Is it safe to drive?

Caution: minimize driving An active P0314 misfire can reduce power and may damage the exhaust system if sustained. Avoid heavy acceleration and long high-load driving until repaired; stop driving if the engine shakes severely, the check-engine light flashes, or power drops substantially.

Typical symptoms

  • The check-engine light may illuminate and store P0314.
  • The engine may develop a slight stumble or shake at idle.
  • Acceleration may feel hesitant or lack its usual response.
  • Engine roughness may become more noticeable under load or at higher engine speed.
  • Fuel economy may decrease because the affected cylinder is not burning efficiently.
  • An unburned-fuel odor or exhaust-system damage may develop if the P0314 misfire continues.

Common causes

  • A defective ignition coil, contaminated spark plug, or resistive ignition connector on one cylinder can cause the single-cylinder misfire reported by P0314.
  • A dirty, leaking, or electrically impaired injector may deliver an incorrect fuel charge to one cylinder and trigger P0314.
  • Low cylinder compression from worn piston rings, valve seats, a damaged valve, or a head gasket problem can produce the condition detected under P0314.
  • An intake or exhaust leak near one cylinder can create a lean mixture or incorrect exhaust flow that appears as a P0314 misfire.
  • Incorrect cam or valve timing can prevent one cylinder from producing normal combustion and contribute to a P0314 event.
  • Damaged wiring, poor grounds, or an intermittent engine-position signal can make the controller misidentify a single cylinder as misfiring.

How to diagnose with an OBD scanner

  1. Capture the code and related data Connect an ELM327-based OBD2 scanner and use AIScanAuto or equivalent software to save stored and pending codes, freeze-frame information, and any cylinder-specific codes before clearing them. A related code such as P0301 through P0306 may identify the cylinder that P0314 itself does not specify.
  2. Identify the affected cylinder Use scanner data for ignition events, injector activity, cylinder contribution, oxygen-sensor response, and short-term fuel trim if available. Confirm the cylinder with a lab scope or an approved one-cylinder disable test; do not disconnect an ignition coil or injector while the engine is running.
  3. Test the ignition system Remove and inspect the spark plugs one at a time for cracks, oil fouling, carbon deposits, excessive wear, and an incorrect electrode gap. Test the coil, connectors, and any fitted high-tension leads, then verify that a strong spark is present at the suspect cylinder.
  4. Check fuel delivery Measure fuel pressure, inspect the injector connector and injector tip, and compare injector pulse and duration with the other cylinders. Review fuel-trim and oxygen-sensor data for evidence that the cylinder is running excessively lean or rich.
  5. Check compression and sealing Perform a compression and leak-down test on the suspect cylinder. If compression is low, inspect valve sealing, piston rings, head-gasket integrity, and valve timing. A smoke test can also reveal an intake or exhaust leak that affects combustion.
  6. Repair and verify the P0314 repair Correct the failed component or mechanical fault, then clear the codes with the OBD2 scanner. Complete a representative drive cycle and confirm that the misfire counter no longer rises and P0314 does not return. If the misfire ran for an extended period, also evaluate the catalytic converter and exhaust system.

Approximate repair cost

Typical independent-shop estimates for diagnosing and repairing P0314 are about $100 to $1,500 USD, depending on whether the fault is an ignition part, injector, wiring issue, or internal mechanical repair. These figures are estimates and vary by region, vehicle configuration, and labor rates.

Common questions

Does P0314 identify which cylinder is misfiring?

Not by itself. P0314 reports a single-cylinder misfire without specifying the cylinder; related P0301-P0306 codes, scan data, or physical testing may identify it.

Can P0314 be caused by something other than a bad spark plug?

Yes. P0314 can result from a defective coil, injector, ignition wiring, low compression, valve-timing error, or an intake or exhaust leak affecting one cylinder.

Is it safe to drive with an active P0314 code?

Brief low-load driving may be possible if the engine runs smoothly, but continued operation can damage the catalytic converter. Avoid sustained high load and stop if severe roughness or a flashing check-engine light appears.

Why does P0314 sometimes return after the repair?

P0314 may return if the original fault was not fully corrected, a pending misfire remains, or the scanner codes were cleared without a complete drive cycle. Verify live misfire counters and monitor the repaired cylinder under load.

When your scan tool pulls a P0314 code, the vehicle's engine control module has identified a single-cylinder misfire but cannot pinpoint exactly which cylinder is responsible. This is different from codes like P0301 or P0304 that identify a specific cylinder. P0314 falls under the powertrain category within the OBD2 standard, specifically within the engine misfire monitoring system.

The control module detects misfires by monitoring crankshaft acceleration. Each power stroke should accelerate the crankshaft smoothly; when one cylinder fails to fire properly, the crankshaft slows momentarily, and the ECM catches this deviation. To set P0314, the module evaluates these readings against factory-calibrated thresholds, typically requiring the pattern to repeat across multiple drive cycles before logging the fault. When the code sets, the ECM also captures a freeze frame snapshot containing RPM, engine load, coolant temperature, and vehicle speed at the moment of failure. This data is invaluable because it reproduces the exact operating conditions under which the misfire occurred, helping you narrow down the root cause faster.

Understanding why the ECM cannot identify the specific cylinder is key to diagnosing P0314. The misfire may be intermittent, borderline, or influenced by factors that affect multiple cylinder readings simultaneously—such as fuel pressure irregularities or crankshaft position sensor glitches. Rather than pointing directly at one cylinder, the system flags a general single-cylinder fault, requiring you to dig deeper through live data and systematic testing.

Common Symptoms of P0314

The symptoms of P0314 overlap with many other misfire codes, but recognizing them helps confirm you're on the right track:

  • Check Engine Light illuminates or flashes intermittently
  • Noticeable exhaust odor, often described as raw fuel smell
  • Fuel economy drops noticeably compared to normal driving patterns
  • Reduced engine power, especially during acceleration
  • Rough idle with noticeable vibration or shaking coming from the engine bay
  • In severe cases, the engine may run unevenly or hesitate under load

Possible Causes of P0314

Several underlying issues can trigger P0314. These are listed from most to least frequently encountered:

  • Fuel injector problems, including clogging or internal leakage that disrupts proper fuel delivery to one cylinder
  • Malfunctioning crankshaft or camshaft position sensor, which disrupts ignition timing and fuel injection synchronization
  • Worn, fouled, or improperly gapped spark plugs that fail to ignite the air-fuel mixture consistently
  • Low or inconsistent fuel pressure caused by a weak fuel pump, clogged filter, or pressure regulator failure
  • Ignition coil or coil-on-plug assembly showing signs of intermittent breakdown
  • Vacuum leaks introducing excess air into the combustion chamber
  • Internal engine mechanical issues such as low compression in a single cylinder

How to Diagnose P0314

Follow these systematic steps to isolate the root cause without replacing parts unnecessarily:

  1. Connect an OBD2 scanner and confirm P0314 is stored. Record the freeze frame data—this snapshot tells you RPM, load, coolant temperature, and speed when the fault occurred. Replicate those exact conditions during your test drive.
  2. Check for additional diagnostic trouble codes. P0314 frequently appears alongside P0300 (random misfire) or other cylinder-specific codes. Also search for manufacturer TSBs (technical service bulletins) related to your make, model, and year—some misfire patterns have known factory remedies or software updates.
  3. Perform a visual inspection of wiring harnesses and connectors feeding the fuel injectors, ignition coils, and crankshaft position sensor. Look for damaged insulation, corrosion, broken terminals, or loose connections that could cause intermittent signals.
  4. Access live data on your scanner and monitor per-cylinder misfire counters while the engine is running. This data often reveals which cylinder is actually misfiring, despite the generic P0314 designation.
  5. Perform a swap test: move ignition coils or fuel injectors to different cylinders and observe whether the misfire migrates with the part. If the misfire follows a swapped component, that part is faulty.
  6. Clear the code after your inspection and repair, then complete a full drive cycle under the freeze frame conditions. Verify P0314 does not return—this confirms the fix is complete.

Repair Options and Costs

Once you've identified the faulty component, repair costs vary significantly based on the part and labor rates in your area. Typical ranges at independent shops (parts and labor, USD):

  • Replace ignition coil or coil-on-plug assembly: $150–$380
  • Replace spark plugs (all four, if applicable): $90–$250
  • Clean or replace a single fuel injector: $200–$600
  • Engine mechanical repair for compression issues: $800–$2,500

The total cost to resolve P0314 typically falls between $90 and $2,500 depending on which part failed. Always begin with the least expensive components—spark plugs and ignition coils—before moving to fuel injector or engine mechanical work. Proper diagnosis upfront prevents wasted money on parts you do not need.

Driving Safety Verdict

Severity: Caution. While the engine may run well enough to drive short distances, an active misfire condition should not be ignored. Unburned fuel entering the exhaust stream can overheating the catalytic converter and cause permanent damage within a few hours of operation. If the Check Engine Light is flashing rather than steady, stop driving immediately—this indicates a severe misfire that risks immediate catalytic converter failure. Have the vehicle diagnosed as soon as reasonably possible to avoid costly secondary damage.

Related OBD2 Codes