Code
P1362
FORD
P — Powertrain
Ignition Coil C Secondary Circuit Malfunction
AI status
Completed
Completed
100%
Causes
- Failed ignition coil (coil C)
- Damaged or fouled spark plug or ignition boot
- Open, shorted, corroded or loose wiring/connectors in coil C secondary/coil pack circuit
- Poor ground or low battery/charging system voltage
- Internal PCM/ignition driver fault (less common)
- Moisture, oil, or carbon tracking causing arcing in the coil/boot assembly
Symptoms
- Malfunction Indicator Lamp (MIL) illuminated
- Rough idle or engine misfire (often cylinder-specific)
- Loss of power, hesitation or stumble under load
- Poor fuel economy and increased emissions
- Hard start or intermittent no-start in some cases
- Audible popping/backfire in intake/exhaust under some conditions
What to check
- Read freeze-frame and stored DTCs and note misfire counters/which cylinder reported
- Check for related codes (ignition/coils/misfire)
- Inspect coil C, spark plug, boot and surrounding area for damage, oil or moisture
- Visually inspect wiring harness and connector for corrosion, loose pins, melted insulation or chafing
- Measure battery and charging system voltage while cranking/idle
- Use a scan tool to monitor coil status, dwell time, and misfire counts
Signal parameters
- Primary coil resistance (typical): ~0.4–2.0 ohms (varies by design)
- Secondary coil resistance (typical): ~3000–15,000 ohms (varies by design)
- Expected coil primary voltage: battery voltage (~11–14.5 V) to the coil supply (VB) when key on
- Secondary spark voltage: several kilovolts at the plug cap under load (measured with appropriate HV probe)
- PCM coil driver: pulsed ground or supply with dwell control — dwell typically 1–5 ms depending on RPM and load (use scope to verify)
Diagnostic algorithm
- Record all stored codes, freeze frame data and live misfire counts with a scan tool
- Perform a visual inspection: coil C, boot, plug, wiring and connectors for damage, corrosion or contamination
- Swap coil C with a known-good coil (another cylinder) and clear codes — if code follows coil, replace coil
- Remove and inspect/replace spark plug and ignition boot for damage or fouling
- Measure coil primary and secondary resistance and compare to manufacturer specification
- With a lab scope (preferred) capture primary and secondary waveforms for coil C and compare to a good cylinder; look for weak or absent secondary spike, truncated wave or excessive leakage
- Check connector pin voltage (VB) and continuity to PCM; check for shorts to ground or battery using backprobe and multimeter/ohm meter
- Inspect and repair wiring harness as needed (repair broken wires, pins, repair insulation, replace connector)
- If wiring and coil check good and problem persists, test PCM coil driver output; consider PCM replacement or reflash only after confirming harness/coil are OK
- After repairs clear codes and test drive; monitor for reappearance and verify misfire count returns to normal
Likely causes
- Faulty coil-on-plug assembly or coil pack for cylinder C
- Worn or fouled spark plug or cracked ignition boot allowing misfire/arcing
- Connector corrosion or broken wire in the coil secondary/high-voltage circuit
- Short to battery voltage or short to ground in coil control/secondary wiring
- PCM driver failure after ruling out wiring and coil issues
Fault status
Status
Ignition Coil C secondary circuit malfunction detected — possible misfire; MIL set.
Repair difficulty: Medium
Diagnostic time: 0.5 - 2.5 hours
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