P0206 on the LML Duramax indicates the engine control module has found an electrical problem in the injector circuit for cylinder 6. The 2011-2016 LML uses Bosch piezo common-rail injectors fed by the CP4.2 high-pressure pump, so injector circuit integrity is important for both power and smooth running. Here is how to understand and correct the code.
What P0206 means
P0206 is defined as "Injector Circuit/Open - Cylinder 6." The ECM drives each injector with a precise electrical pulse and watches the current in that circuit. If the cylinder 6 circuit is open, shorted, or reading outside the expected range, P0206 sets. On the LML the injectors are piezo units that require flow-rate calibration codes, so an accurate diagnosis has to separate wiring problems from a genuinely failed injector.
Common causes
- Damaged or corroded injector connector under the valve cover
- Chafed, pinched, or broken injector harness wiring
- An internally failed piezo injector for cylinder 6
- Oil intrusion into the connector body
- Loose or spread terminals at the ECM
- Injector driver fault inside the ECM (uncommon)
Symptoms
- Check engine light with P0206 stored
- Rough idle and a detectable miss
- Loss of power and hesitation under acceleration
- Hard start or long cranking
- Excess smoke or a fuel smell
- Possible reduced engine power mode
How to diagnose it
Scan for all stored codes; when several injector codes appear at once, a shared harness or connector is the likely cause. Remove the valve cover as needed to inspect the injector harness for chafe points and oil-soaked, corroded connectors. Verify wiring continuity from the cylinder 6 injector back to the ECM, and check terminal tension. Use a scan tool that supports injector balance and cylinder contribution data to confirm whether cylinder 6 is dropping out. Because these are piezo injectors, follow the factory electrical test rather than a simple resistance check.
How to fix it
Repair or replace damaged wiring and connectors first. If the injector itself is confirmed bad, replace it and program the new injector's flow-rate calibration code into the ECM so the engine meters fuel correctly. The LML valley harness and connectors are a known trouble spot, so inspect the neighboring cylinders while you have access. Clear codes and road test under load to confirm the repair.
FAQ
Are LML Duramax injectors piezo or solenoid?
The LML uses Bosch piezo common-rail injectors, which require a calibration code to be programmed after replacement.
Can bad wiring cause P0206 by itself?
Yes. Chafed harness wires and corroded connectors in the valley are common causes, so test the circuit before replacing the injector.
Should I replace all injectors at once?
Not necessarily. If only cylinder 6 is failing and the others test fine, you can replace just the one, but inspect the harness and neighboring connectors while you are in there.
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