Code
P1338
DAEWOO
P — Powertrain
#8 MISFIRE CIRCUIT - OPEN
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UK: 0
EN: 6
RU: 2
AI status
Completed
Completed
100%
Causes
- Open or broken wiring between ignition coil/module and ECM
- Faulty ignition coil or coil-on-plug pack (cylinder 8)
- Faulty ignition module/igniter or coil driver in ECM
- Poor or corroded connector(s) at coil, grounding point, or ECM
- Damaged spark plug or poor plug connection
- Aftermarket ignition component or improper installation
Symptoms
- Check Engine Light (MIL) on
- Rough idle or vibration
- Reduced power, hesitation on acceleration
- Possible poor fuel economy
- Misfire detected specifically on cylinder 8 (may show codes like P0308 along with P1338)
What to check
- Read freeze frame and live data with a scan tool. Confirm misfire counts and whether P0308 or other misfire codes are present.
- Visual inspection of coil, connector, wiring harness for damage, corrosion, or loose pins at cylinder 8.
- Wiggle test connectors and harness while monitoring live ignition/status data for intermittent changes.
- Swap coil from cylinder 8 with another cylinder to see if misfire/circuit code follows the coil.
- Measure coil primary and secondary resistance per service specifications.
- Verify power and ground at coil connector with ignition ON/cranking.
Signal parameters
- Battery/coil supply voltage: ~11–14.5 V with ignition ON/cranking
- Coil primary switching: pulse to ground from ECM; voltage toggles between near battery voltage and low (close to 0 V) when fired
- Primary coil resistance (typical): 0.5–2 Ω for many modern ignition coils (consult vehicle spec)
- Secondary coil resistance (typical): 5 kΩ–15 kΩ (consult vehicle spec)
- Ignition dwell/pulse width: a few milliseconds (depends on rpm/load)
- No primary/secondary pulse expected at coil when circuit is open
Diagnostic algorithm
- Retrieve DTCs and freeze frame. Note related codes (P0308, P0300, P0358, etc.).
- Perform visual inspection: inspect cylinder 8 coil, spark plug, connector, and wiring for obvious damage or corrosion.
- With connector disconnected, check for proper battery voltage at coil power terminal with ignition ON.
- Back-probe coil primary terminal while cranking/starting to check for switching pulse from ECM; if no pulse, confirm continuity to ECM.
- Measure coil primary and secondary resistance and compare to spec. Replace coil if out of spec or if swapping moves the misfire/code to another cylinder.
- If coil, wiring and connectors are good, check continuity between coil driver pin and ECM; inspect ECM connector pins and grounds.
- If wiring and coil are confirmed good and no ECM driver pulse, consider ECU/ignition module fault and consult service manual for ECU tests or replacement procedures.
- After repairs, clear codes and road-test. Re-check for reoccurrence and verify misfire correction with scan tool.
Likely causes
- Damaged harness or connector at cylinder 8 coil
- Failed coil pack or coil-on-plug assembly for cylinder 8
- Faulty coil driver inside ECU (less common)
- Loose/failed spark plug or plug wire (if applicable)
- Corroded ground or power supply to ignition coils
Fault status
Status
Ignition/misfire circuit for cylinder 8 shows an open condition — no ignition pulse detected for that cylinder.
Repair difficulty: Medium
Diagnostic time: 0.5-2.5 hours
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