Code
P1346
DAEWOO
P — Powertrain
#6 ION CIRCUIT
Views:
UK: 3
EN: 8
RU: 7
AI status
Completed
Completed
100%
Causes
- Open or shorted wiring between ignition coil #6 and engine control module (ECM)/ignition control module (ICM)
- Corroded, loose, or damaged connector at coil #6
- Failed ignition coil or coil pack for cylinder #6
- Contamination (oil, coolant, fuel) on coil or spark plug affecting ion sensing
- Faulty spark plug or high secondary resistance (or worn plug)
- Failed ECM/ignition module driver for the ion circuit
Symptoms
- Malfunction Indicator Lamp (MIL) / check engine light ON
- Possible misfire felt on cylinder #6 or rough idle
- Reduced power, poor acceleration or hesitation under load
- Increased fuel consumption and higher emissions
- Diagnostic trouble code P1346 stored; may be accompanied by misfire codes (e.g., P0306)
What to check
- Read and record freeze frame data and stored codes with a scan tool
- Visual inspection of ignition coil #6, spark plug and connector for damage, corrosion or contamination
- Check for related misfire codes (P0306) and ignition coil circuit codes (P0356)
- Backprobe coil #6 connector and check for power/ground and signal using a multimeter or oscilloscope
- Inspect harness for chafing, melted insulation, or signs of shorting to ground or battery voltage
- Swap coil #6 with a known good coil from another cylinder to see if the code follows the coil or stays with cylinder
Signal parameters
- Expected: ion/current pulse at ignition event synchronized with spark (pulse amplitude and polarity vary by system)
- Primary coil supply: normally battery voltage (~11–14 V with engine running) on primary supply pin
- Coil primary resistance: manufacturer specific (typical small value, e.g., 0.5–2 Ω); secondary resistance: higher (kΩ range)
- When healthy: oscilloscope shows a characteristic ion/current waveform immediately after spark. Absent, flat, reversed, or noisy waveform indicates fault
Diagnostic algorithm
- Connect a scan tool, read all codes and freeze frame data. Note any related misfire or ignition coil codes.
- Visually inspect coil #6, spark plug, and wiring harness. Repair or replace damaged connectors or pins.
- Clear the code and perform a key-on engine-off (KOEO) and key-on engine-run (KOER) test to try to reproduce the fault while monitoring live ion/current data if available.
- Backprobe coil #6 supply and ground pins with a multimeter: verify battery voltage on supply and good ground. Check for intermittent voltage loss while cranking.
- Measure coil primary and secondary resistance and compare to specifications. Replace coil if out of spec.
- Swap coil #6 with another cylinder’s coil. If code follows the coil, replace the coil. If it remains on cylinder #6, suspect wiring or ECM.
- Use an oscilloscope to view the ion-sensing waveform at coil #6 during cranking and running. Compare to a known-good waveform on another cylinder.
- Check continuity of signal wiring from coil #6 to ECM and check for shorts to ground or battery. Repair any damaged wires or connectors.
- If wiring and coil test good and problem remains, check ECM grounds, power supply, and then consider ECM/ignition module failure — confirm with manufacturer procedures before ECM replacement.
- After repairs, clear codes and road test to verify the fault does not return.
Likely causes
- Intermittent open/short in coil #6 harness or connector
- Ignition coil #6 internal failure (ion-sensing element or driver)
- Corrosion or water ingress at coil connector preventing ion signal
- ECM driver transistor for cylinder #6 failed
- Spark plug fouled or damaged preventing ion current formation
Fault status
Status
PCM detects missing/abnormal ion-sensing signal from cylinder #6. This stores DTC P1346 and may illuminate MIL; requires inspection of coil, plug, wiring, and ECM circuitry.
Repair difficulty: Medium
Diagnostic time: 0.5-2.0 hours
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