Code
P1343
DAEWOO
P — Powertrain
#3 ION CIRCUIT
Views:
UK: 2
EN: 7
RU: 4
AI status
Completed
Completed
100%
Causes
- Open, shorted, or corroded wiring/connectors in the #3 ion/ignition circuit
- Faulty ignition coil or coil pack on cylinder 3
- Damaged or fouled spark plug in cylinder 3
- Poor ground or power supply to coil/ion sensing circuit
- ECM/PCM internal fault or failed ion-sensing input
- Mechanical problems in cylinder 3 (severe compression loss, valve issue)
Symptoms
- Malfunction Indicator Lamp (MIL) illuminated
- Engine hesitation or rough idle, especially under light load
- Misfire stored or felt on cylinder 3
- Reduced fuel economy or loss of power
- Hard starting or stumble immediately after start (occasionally)
What to check
- Retrieve freeze frame and live data with a scan tool; check misfire counters and ion-signal channel for cylinder 3 if available
- Visually inspect wiring and connectors at ignition coil #3 and ECM; look for corrosion, damage, or loose terminals
- Inspect spark plug for fouling, excessive wear, or damage; check gap
- Perform coil swap: move coil from cylinder 3 to another cylinder and see if code or misfire follows the coil
- Check continuity and resistance of ion/coil harness between coil and ECM, and check for shorts to ground/12V
- Verify engine and ECM grounds are clean and tight
Signal parameters
- Signal type: low-voltage ion-current pulse or secondary ignition-derived signal from cylinder 3
- Timing: pulses should occur synchronous with spark events for cylinder 3
- Normal characteristic: measurable, repeatable pulses during and immediately after combustion; amplitude and shape vary with combustion quality
- Fault indication: missing, very low amplitude, irregular, or out-of-timing pulses for cylinder 3
Diagnostic algorithm
- Connect a scan tool and read freeze frame/live data. Note conditions when the code set (RPM, load, temperature). Clear the code and perform a drive cycle to reproduce.
- Perform visual inspection of ignition coil #3, spark plug, and harness. Repair any obvious damage or corrosion and re-check.
- Swap the ignition coil from cylinder 3 with another cylinder. If the code or misfire follows the coil, replace the coil.
- Swap the spark plug with a known-good plug or inspect/replace the plug on cylinder 3. Re-test.
- Check continuity and insulation of the ion-sense/coil signal wiring between coil and ECM. Repair any open or shorted wiring. Check connector pins for tightness and corrosion.
- Using an oscilloscope or suitable scope adapter, observe the ion or secondary ignition waveform at cylinder 3 while cranking/running. Compare with a good cylinder. Look for missing or abnormal pulses.
- Verify engine and ECM grounds and power supply voltages to the ignition module/coil driver. Repair as needed.
- If wiring, coil, and plug are good and waveform remains abnormal for cylinder 3, consider ECM input fault; consult manufacturer service information before replacing ECM.
- After repairs, clear codes and confirm proper operation through a full drive cycle and re-scan for stored codes.
Likely causes
- Loose/corroded connector at coil or wiring harness to cylinder 3
- Failed ignition coil on cylinder 3
- Bad or worn spark plug causing poor ion current path
- Short to ground or short to voltage in ion-sense lead
- Weak or missing ground at engine/ECM
Fault status
Status
Malfunction Indicator Lamp (MIL) set when the ECM detects an abnormal, missing, or out-of-spec ion-sensing signal for cylinder #3. Fault may be intermittent or stored as a confirmed code after detection criteria are met.
Repair difficulty: Medium
Diagnostic time: 1.0 - 3.0 hours
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