P0357

Ignition Coil F Primary/Secondary Circuit Malfunction

Powertrain Ignition System Coil Pack/Ignition Circuit 🟡 Moderate — Fix within a week ⚠️ Drive with Care
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What This Actually Means

In plain language — no jargon

Coil F isn't firing properly—either the primary circuit (which triggers the spark) or secondary circuit (which delivers high voltage) has a problem. It's like a lighter with a broken spring; the ignition won't reliably produce a spark.

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Symptoms You May Notice

3 known symptoms for this code
Cylinder 6 misfire or rough idle
Check engine light illuminated
Reduced engine power or hesitation during acceleration
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How Your ECU Detects This

Technical sensor logic and voltage thresholds

The ECM monitors primary coil current draw and secondary voltage output during ignition events. It detects opens, shorts, or resistance anomalies in the coil pack F circuit by comparing dwell time and feedback voltage against stored thresholds.

Voltage & Parameter Thresholds

ParameterNormal RangeFault Condition
Primary Coil Current Draw 2.0–5.0 amps Below 1.5 amps or above 7.0 amps
Secondary Coil Voltage 25,000–40,000 volts Below 15,000 volts or open circuit
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Diagnostic & DIY Fix Guide

Check these in order — from cheapest to most complex
1
Ignition coil connector/harness
Inspect and reseat the connector to coil F; check for corrosion, moisture, or loose pins.
2
Spark plug wire or boot (coil F)
Replace the high-tension wire or boot connecting coil F to cylinder 6 spark plug if cracked or burned.
3
Ignition coil pack F
Replace the entire coil pack if primary or secondary resistance is out of spec or continuity is broken.
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When to See a Professional Mechanic

Not all fault codes are safe to DIY

Code P0357 is a moderate fault. You can generally drive to a workshop, but avoid long trips or high-load driving (motorway, uphill towing) until it is diagnosed. If the code keeps returning after clearing, or if you notice the symptoms listed above worsening, do not delay professional diagnosis. Many moderate codes have multiple possible root causes — a mechanic with live OBD data can identify the exact fault more efficiently than part-by-part trial and error.

Safety note: OBD-II codes identify the system or circuit where a fault was detected — they do not always identify the exact failed component. A professional mechanic using live sensor data will diagnose the root cause more accurately than replacing parts based on the code alone.
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How to Clear Code P0357

What happens after you fix the fault

Once the fault is repaired, P0357 can be cleared using any OBD-II scanner. Connect the scanner, navigate to "Clear Codes" or "Erase DTCs," and confirm. The check engine light turns off immediately.

The code will return if the root cause was not actually fixed. The ECM re-detects the fault within 1–3 drive cycles and sets the code again.

✅ Safe to Clear When
  • Fault has been diagnosed and repaired
  • You want to confirm the repair worked
  • Code appeared after a sensor was cleaned
⚠️ Do Not Clear When
  • Preparing for an emissions/PUC test
  • Root cause is still undiagnosed
  • Check engine light is flashing
Emissions test note: Clearing codes resets OBD readiness monitors. Most vehicles need 50–100 km of mixed driving before monitors complete. Do not clear codes immediately before an emissions or PUC inspection.