P0357
Ignition Coil G Primary/Secondary Circuit
If your vehicle's onboard computer has flagged the diagnostic trouble code P0357, it refers to a detected anomaly regarding "Ignition Coil G Primary/Secondary Circuit". This systemic engine fault needs a targeted check before symptoms expand.
Driver's Summary
Code P0357 means your vehicle detected a problem with the ignition coil g primary/secondary circuit system. Drivers typically experience engine stumble, flashing mil, lack of power when this code is active. Given the high severity of this code, continuing to drive risks significant mechanical damage. Have it diagnosed immediately.
Symptoms
Engine stumble, flashing MIL, lack of power
Common Causes
- Failed ignition coil G (Cylinder 7)
- Connector damage
- Bad spark plug
- Internal PCM short
How to Fix
- 1 Replace ignition coil G
- 2 Replace connector pigtail
- 3 Replace spark plug
- 4 Test PCM
Technical Explanation
Detection of P0357 occurs when the ECM cross-references multiple sensor inputs and determines that the reported values are physically inconsistent or out-of-range. Misfire rate is counted per cylinder over rolling windows and compared against two thresholds: a catalyst-damaging rate (triggers flashing MIL) and an emissions-exceeding rate (triggers solid MIL). The PCM logs which cylinder is misfiring based on crankshaft position at the time of each detected event. The MIL illuminates after the fault is confirmed on two consecutive drive cycles, and the freeze frame data captured at first detection is stored in the PCM's memory for diagnostic reference.
Is It Safe to Drive?
Driving with an active P0357 fault risks accelerating damage to failed ignition coil g (cylinder 7) and related components. The longer the fault persists, the more expensive the eventual repair becomes — what starts as a sensor or solenoid issue can escalate to major mechanical failure.
Mechanic's Pro Tip
The fastest isolation technique for P0357 is the coil swap test: move the ignition coil from the affected cylinder to a neighboring cylinder and clear the code. If the misfire follows the coil, it's the coil. If it stays on the same cylinder, focus on the spark plug, injector, or compression. Never replace coils without also replacing the spark plug in that cylinder — a fouled plug will kill a new coil within weeks.
Ignition coil: $80 - $200