Code
P0362
GWM
P — Powertrain
- Malfunction in the primary / secondary circuit of the ignition coil L
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AI status
Completed
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Causes
- Failed ignition coil (internal open/short)
- Damaged or corroded coil connector or pins
- Open, shorted, or high-resistance wiring in primary or secondary circuit
- Faulty spark plug or incorrect gap
- Moisture, oil, or contamination causing secondary leakage/short
- Faulty ECM/ignition driver (less common)
Symptoms
- Malfunction Indicator Lamp (MIL) illuminated
- Rough idle or engine vibration
- Misfire on one cylinder (possible loss of power)
- Hesitation or poor acceleration
- Decreased fuel economy
- Hard starting or extended crank time (in some cases)
What to check
- Read stored freeze-frame data and all related diagnostic trouble codes (DTCs). Note occurrence conditions (rpm, load, temp).
- Perform visual inspection of ignition coil L, boot, spark plug and harness for damage, oil, or corrosion.
- Check connector pins for corrosion, bent pins or poor contact; inspect for water ingress.
- Verify battery voltage and engine ground integrity before testing coil circuits.
- Swap coil L with a known-good coil of another cylinder and see if the code or misfire follows the coil (if safe and practical).
- Measure primary and secondary resistances of the coil with the coil removed and power disconnected, comparing to manufacturer specs.
Signal parameters
- Primary coil resistance (typical range, manufacturer-specific): ~0.3–2.0 ohms (measure with coil disconnected).
- Secondary coil resistance (typical range, manufacturer-specific): ~3,000–15,000 ohms (varies widely by coil type).
- Primary circuit: pulsed 12 V supply with ECM switching to ground; observe pulse duty/dwell with oscilloscope.
- Primary waveform: sharp current rise and defined collapse when coil is fired; missing or flat pulses indicate open/driver fault.
- Secondary: high-voltage pulse sufficient to jump spark plug gap (tens of thousands of volts); leakage or low amplitude indicates secondary fault.
- No-load coil current and dwell times are vehicle-specific—compare live waveform to known-good reference.
Diagnostic algorithm
- Read codes and freeze-frame. Note related misfire codes (P030x).
- Visually inspect coil L, boot, spark plug, wiring harness and connector for damage, contamination, or loose pins.
- Check battery voltage and engine chassis ground; low voltage or poor ground can cause spurious coil faults.
- With ignition off and battery disconnected or following manufacturer safety, disconnect the coil and measure primary and secondary resistance. Compare to OEM specs. Replace coil if out of range.
- Inspect and/or replace the spark plug associated with coil L if fouled, cracked or gap incorrect.
- Swap coil L with a coil from another cylinder. Clear codes and run engine. If code/misfire moves to the other cylinder, the coil or boot is suspect.
- If coil appears good, inspect harness continuity and for shorts to ground or battery using a multimeter. Repair any damaged wiring or corroded terminals.
- Reconnect and with safe procedures use an oscilloscope or appropriate diagnostic tool to view the primary waveform while cranking/running. Look for proper drive pulses and waveform shape. An absent or abnormal waveform suggests ECM driver or wiring issue.
- If wiring and coil are good but waveform indicates ECM driver fault, confirm with manufacturer diagnostic flow; consider ECM replacement only after exhaustive verification.
- After repairs, clear codes and perform a test drive to confirm the fault does not return and that misfire symptoms are resolved.
- Safety: ignition systems produce high voltage. Disconnect battery or follow manufacturer safety procedures before performing continuity/resistance checks. Use insulated tools and appropriate testers for live high-voltage checks.
Likely causes
- Defective ignition coil L
- Damaged wiring harness to coil L (chafing, crushed, rodent damage)
- Corroded/loose coil connector or terminal
- Worn or fouled spark plug on the same cylinder
- Contamination on coil boot causing arcing
- Intermittent ECM driver fault
Fault status
Status
Ignition coil L primary/secondary circuit malfunction detected. Possible causes include a failed coil, wiring/connector fault, fouled spark plug, or an ECM driver issue. Engine may misfire and the MIL will be illuminated.
Repair difficulty: Medium
Diagnostic time: 0.5-2.0 hours
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