P1371 — Ignition Spare

For Ford vehicles

ignition spare - cylinder 1 – fault detected

powertrain (engine/transmission)

Is it safe to drive?

Drive with caution Drive with caution and avoid load. Ignition faults cause misfires that quickly overheat and destroy the catalytic converter; if the Check Engine Light flashes, stop and fix it first.

How to diagnose with an OBD scanner

  1. Read the code and freeze frame Connect an OBD2 scanner, confirm P1371 is stored, and save the freeze frame data — it shows engine conditions when the fault was detected.
  2. Check for companion codes and TSBs Related codes often reveal the real root cause. Also check manufacturer technical service bulletins (TSB) for your make and model — many P0xxx issues have factory fixes or software updates. Search by VIN on the manufacturer site or nhtsa.gov.
  3. Inspect wiring and connectors Visually inspect the wiring harness and connectors related to the ignition system for damage, corrosion, chafing or poor contact.
  4. Subsystem check Swap the coil to another cylinder and see if the fault code follows it.
  5. Subsystem check Inspect spark plugs for wear, oil or carbon tracks and check plug gaps.
  6. Verify the repair Clear the code, complete a full drive cycle including the conditions from the freeze frame, and confirm P1371 does not return.

Approximate repair cost

Repair cost depends on which component actually failed. Typical scenarios for P1371 (parts and labor, USD, independent shop rates): Replace spark plugs: $90–$250; Repair coil wiring or connector: $80–$250; Replace an ignition coil: $150–$380. Overall, fixing P1371 usually costs between $80 and $380. An accurate diagnosis before buying parts saves money — the most expensive scenario is rarely the first one to check.

Common questions

What is the most common cause of P1371?

The most common causes are: worn spark plugs or wrong plug gap, damaged coil wiring or connector, failed ignition coil or coil pack.

Is it safe to drive with P1371?

Drive with caution and avoid load. Ignition faults cause misfires that quickly overheat and destroy the catalytic converter; if the Check Engine Light flashes, stop and fix it first.

What are the symptoms of P1371?

Drivers most often notice: loss of power and jerking, increased fuel consumption, Check Engine Light on, hard starting, especially in damp weather.

What does OBD2 code P1371 mean?

Ignition Spare (P1371): a powertrain (engine/transmission) fault affecting the ignition system. Short, gentle driving to a shop is usually possible. Most often caused by worn spark plugs or wrong plug gap, damaged coil wiring or connector, failed ignition coil or coil pack.

How much does it cost to fix P1371?

Replace spark plugs — $90–$250; Repair coil wiring or connector — $80–$250; Replace an ignition coil — $150–$380. Exact cost depends on the root cause, your vehicle and local labor rates — a proper diagnosis is the cheapest first step.

When your engine control unit detects that the ignition system is not firing correctly, it logs OBD2 code P1371. The official definition for this powertrain code is "Ignition Spare," which means the PCM has noticed an unexpected pattern in how the ignition coils are being triggered. This is not a sensor failure — it's an electrical or mechanical problem with the spark delivery system itself. The ignition system on most engines works by having the PCM send a low-voltage signal to an ignition coil, which then amplifies that signal into the high-voltage current that jumps the gap at each spark plug. When something interrupts this process, the engine runs poorly and the PCM records a fault.

The PCM does not set P1371 based on a single bad reading. It requires the fault condition to repeat under specific operating conditions before the check engine light illuminates. This is intentional — it prevents false alarms from one-time electrical glitches. When P1371 is stored, the freeze frame data accompanying it is your most valuable diagnostic clue. This snapshot captures engine load, RPM, coolant temperature, and vehicle speed at the exact moment the fault occurred. Recreating those conditions during testing allows you to observe the problem firsthand rather than guessing where it hides.

The ignition spare code signals that the engine management system has lost confidence in the ignition timing or coil firing sequence. This can happen because a coil is failing internally, wiring is breaking down under heat and vibration, or the PCM itself is having trouble controlling the ignition circuit. Moisture intrusion into the engine compartment is a common trigger, especially in older vehicles where rubber seals dry out and crack.

Common symptoms of P1371

  • Noticeable loss of engine power with hesitation or jerking during acceleration
  • Fuel economy drops noticeably compared to normal driving habits
  • Check engine light remains solid on the dashboard
  • Engine cranks slowly or fails to start in damp or rainy conditions
  • Cylinder misfires occur either while idling or under heavier loads
  • Rough idle with noticeable vibration through the accelerator pedal

What causes P1371?

  • Failed ignition coil or entire coil pack assembly
  • Damaged wiring harness or loose connector at the ignition coil
  • PCM malfunction affecting the ignition control signal circuit
  • Moisture or engine oil seeping into the spark plug well tubes
  • Worn spark plugs with incorrect gap spacing
  • Corroded or broken terminals in the ignition coil connector

How to diagnose P1371

  1. Connect a quality OBD2 scanner and confirm P1371 is present in the stored codes. Record the freeze frame data immediately — this tells you the engine load, RPM, and temperature when the fault was first detected.
  2. Pull all other stored codes from the ECU. Related misfire codes, fuel trim codes, or additional ignition-related faults often point directly to the root cause. Check for any factory technical service bulletins applying to your specific vehicle make, model, and year.
  3. Perform a thorough visual inspection of the ignition coil wiring and connectors. Look for cracked insulation, wire chafing from contact with engine brackets, green corrosion on terminals, or any connectors that are not fully seated.
  4. Test the suspected coil by swapping it with a known-good unit from another cylinder. If the fault code migrates to the new cylinder, the coil itself is faulty.
  5. Remove and inspect all spark plugs in the affected bank. Check for oil fouling, carbon buildup, worn center electrodes, or gaps that do not match manufacturer specifications.
  6. Clear the code and perform a complete drive cycle that includes the exact operating conditions recorded in the freeze frame. If P1371 returns, the root cause has been confirmed and repaired.

Repair options and costs

Replacing worn spark plugs typically runs $90 to $250 including parts and labor at an independent shop. Fixing damaged coil wiring or replacing a faulty connector usually costs between $80 and $250 depending on whether the harness can be repaired or needs a new assembly. Swapping out a failed ignition coil is the most expensive repair in this range, costing $150 to $380 for the component and installation.

The total cost to repair P1371 typically falls between $80 and $380 depending on which component is actually at fault. Diagnosing the problem correctly before purchasing any parts is the smartest move — the most expensive scenario is rarely the first one you should check. A mechanic can often confirm the faulty coil with a simple swap test in under fifteen minutes.

Can you drive with P1371?

Use caution when driving with this code stored. Ignition misfires allow unburned fuel to enter the exhaust system, where it ignites inside the catalytic converter and overheats it rapidly. Continued operation can destroy an expensive emissions component. If the check engine light is flashing rather than solid, stop driving immediately and have the vehicle towed — a flashing CEL indicates an active misfire that requires urgent attention.