P0268: Cylinder 3 Fuel Injector Circuit High Voltage/Current
Engine misfire, rough idle, reduced power and efficiency
Overview
OBD-II P0268 indicates an electrical issue in the fuel injector circuit for cylinder #3, often high voltage or resistance, causing misfires and fueling imbalance.
Common Symptoms
- Check Engine Light illuminated
- Rough idling
- Engine misfire on cylinder 3
- Reduced engine power and acceleration
- Increased fuel consumption
Most Common Causes
Injector coil resistance outside specification often triggers high draw condition.
Open, short to voltage/ground, or poor connections increase circuit resistance or voltage.
Rare but possible; causes incorrect drive signals or misinterpretation of circuit values.
Less direct but can correlate with injector irregularities on some platforms.
Conflicting community reports; not a primary manufacturer definition cause.
Diagnostic Steps
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Verify code with a scan tool and record freeze frame dataExpected: P0268 present and no other overriding codesInterpretation: Confirms diagnostic starting point
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Perform visual inspection of cylinder #3 injector connector and harnessExpected: No corrosion, broken wires, loose pinsInterpretation: Damaged wiring often causes high voltage/resistance readings
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Measure injector coil resistance with multimeterExpected: Resistance within manufacturer spec (varies by model)Interpretation: Out‑of‑range indicates internal short or open
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Check supply voltage to injector connector with key on (engine off)Expected: Correct battery voltage at supply sideInterpretation: No supply suggests wiring or ECM drive issue
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Use noid light or oscilloscope to check injector pulse while crankingExpected: Regular pulse patternInterpretation: Irregular or absent pulses imply drive circuit fault
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If electrical tests are normal, swap injector with another cylinder (if applicable)Expected: Code follows or staysInterpretation: Helps isolate injector vs wiring/ECM
Repair Solutions
Connector pins, harness repair often resolves high resistance/voltage issues
Injector replacement with correct part recommended
Necessary only if all circuit and injector tests are normal
Common Misdiagnoses
Avoid these common diagnostic mistakes:
- Misinterpreting generic injector misfire codes (e.g. P0303) as the root cause without electrical testing
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