Code
P1344
DAEWOO
P — Powertrain
#4 ION CIRCUIT
Views:
UK: 1
EN: 4
RU: 2
AI status
Completed
Completed
100%
Causes
- Open or shorted wiring to the ion/coil sensor for cylinder 4
- Poor connector or pin contact at the ignition coil or ECU
- Failed ignition coil or coil pack for cylinder 4
- Faulty engine control module (ECM) input circuit
- Internal failure in ion-sensing circuitry or related sensing resistor
- Mechanical issue causing no combustion in cylinder 4 (severe misfire, no compression)
Symptoms
- MIL (Check Engine Light) illuminated and stored P1344
- Intermittent or consistent misfire on cylinder 4 (reduced power)
- Rough idle, vibration, increased fuel consumption
- No ion-sensing/combustion signal for cylinder 4 when monitored
- Possible hard starting or stumble under load
What to check
- Read and record freeze-frame/DTCs and related misfire codes (e.g., P0304)
- Visually inspect ignition coil, plug, wiring, and connector for cylinder 4 for damage, corrosion, or poor seating
- Check for other stored codes that could point to crank/cam or fuel issues
- Swap coil for cylinder 4 with another cylinder (if coils are identical) and see if the fault follows the coil (clears risk of misdiagnosis)
- Use a scan tool or oscilloscope to monitor the ion-sensing/ignition waveform on cylinder 4 compared with a known-good cylinder
- Measure connector continuity and for short to ground/voltage between coil/ion connector and ECM
Signal parameters
- Ion-sensing signal: pulsed waveform coincident with ignition events (present only during cylinder 4 firing)
- Expected: distinct combustion-related spike or pulse; absent, very low amplitude, or noisy waveform indicates fault
- Primary coil drive signal present when cranking or running; absence implies coil or driver issue
- Compare amplitude, pulse shape and timing to a known-good cylinder using an oscilloscope or capable scan tool
Diagnostic algorithm
- Retrieve all DTCs and freeze-frame data; note any misfire or sensor codes. 2) Perform a visual inspection of ignition coil #4, spark plug, wiring harness and connectors for damage, corrosion, loose pins or signs of arcing. 3) If coils are serviceable and identical, swap coil #4 with a coil from another cylinder and clear codes; run engine to see if P1344 or misfire follows the coil. 4) Backprobe the ion/coil signal connector and use a lab scope or oscilloscope to compare the ion-sense waveform on cylinder 4 to a known-good cylinder while cranking and running. 5) Check continuity and resistance of wiring between coil connector and ECM; inspect for short to ground or to battery voltage. 6) Verify proper primary coil drive (control) from ECM; if drive is present but ion signal absent, suspect coil or combustion problem. 7) If no primary drive, investigate ECM outputs, drivers, and upstream signals (crank/cam sensors). 8) If mechanical cause suspected (no combustion signal despite good ignition waveform), perform compression/leakdown test on cylinder 4. 9) Repair or replace faulty wiring, connectors, coil, spark plug, or ECM input module as indicated by tests. 10) After repair, clear codes and road-test to verify the fault does not return.
Likely causes
- Damaged wiring or poor connector to cylinder 4 ion/coil sensor
- Failed ignition coil or coil pack on cylinder 4
- Connector contamination or corrosion at coil or ECU
- ECM sensing circuit fault (less common)
Fault status
Status
Ion circuit fault detected for cylinder 4 — the ECM is not receiving a valid ion/combustion signal from that cylinder. Inspect ignition circuit, wiring, coil, plug, and related sensors.
Repair difficulty: Medium
Diagnostic time: 0.5-3.0 hours
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