Comprehensive diagnostic guide for P0206: Cylinder 6 Injector Circuit Malfunction

Overview

• What the code indicates: P0206 is a powertrain diagnostic trouble code associated with the injector circuit for cylinder 6. In OBD-II systems, injector circuit faults fall under the injector/ignition/fuel delivery subsystem, i.e., a fuel injector in cylinder 6 is not being driven or is not functioning correctly. This is a "powertrain" code in the OBD-II framework.
• Open-source reference note: An open-source entry for suggests an open circuit condition for cylinder 6's injector. This aligns with one common concrete failure mode for P0206.

Symptoms

• MIL (Check Engine Light) illuminated, often with P0206 stored exactly or accompanied by related codes.
• Engine running unevenly or with reduced power, especially under acceleration; possible hesitation or stumble on cylinder 6.
• Rough idle or misfire feel on cylinder 6 (engine vibrations, sometimes felt through the steering wheel or seat at idle).
• Increased fuel consumption or abnormal exhaust symptoms if the misfire persists.
• In some cases, a pending or intermittent P0206 can appear with a P0306 (cylinder 6 misfire) if cylinder 6 is not receiving adequate fuel.
  Notes: These symptom themes reflect typical customer-reported experiences with injector-circuit related DTCs and are consistent with how OBD-II powertrain codes present to technicians.

Probable Causes

Based on typical field experience (ASE-level diagnostic reasoning) and the general nature of P0206, the main causes are usually related to the injector circuit itself or its wiring. If you see no NHTSA data , use practical field experience to gauge probabilities:

• Most common: Cylinder 6 injector open circuit or injector itself failing (stuck open/blocked). 40-50%
• Wiring/connector issues in the injector circuit (damaged insulation, poor crimp, corroded connectors, broken ground or signal return path). 20-30%
• Injector driver/PCM (injector driver transistor or related PCM circuitry fault). 10-20%
• Fuel delivery side issues affecting injector operation indirectly (low fuel pressure, contaminated rail, or supply issues). 5-15%
• Other/common misfire causes less likely but possible (rare PCM synchronization fault, battery voltage drop affecting injector drive, etc.). 0-5%

Safety Considerations

• Fuel system hazards: The fuel system is high-pressure and flammable. Relieve fuel pressure before disconnecting fuel lines or performing injector wiring work. Have a spill-safe environment and proper PPE (gloves, eye protection).
• Electrical safety: Disconnect the battery when performing work on the injector circuit wiring or the PCM; avoid short circuits.
• Emission-system considerations: If you suspect injector issues and the engine has spent long periods running with a misfire, consider risk and inspect emissions-related components after repair.

Required tools and equipment

• OBD-II diagnostic scan tool to confirm P0206 and review freeze-frame data, live misfire/ injector data if available.
• Noid light or injector test light (to confirm injector drive signal from PCM to cylinder 6 injector).
• Digital multimeter (for resistance checks on the injector coil and for continuity/voltage tests in the injector circuit).
• Scan scope or lab scope (optional but highly useful for watching injector pulse width/duty cycle and to verify consistent signals).
• Fuel pressure gauge (to verify rail pressure and ensure the injector is being supplied properly).
• Vehicle service manual or manufacturer data for injector coil resistance and the proper test procedures.
• Basic hand tools for connector access and potential connector cleaning/reseating.

Diagnostic procedure (step-by-step)

1) Confirm and record data

• Use the scan tool to confirm P0206 exists and note engine load, RPM, fuel trim data, misfire counters, and freeze-frame data.
• Check for any related codes (e.g., P0306 for a misfire on cylinder 6) to understand whether the problem is purely injector-related or a broader misfire issue.

2) Visual inspection and basic wiring check

• Inspect injector 6 wiring harness and its connector for damage, fraying, pin corrosion, water intrusion, or loose connections.
• Look for signs of corrosion at the injector connector and at the PCM injector-driver circuit; check vehicle grounds and battery connects as poor grounding can affect injector operation.
• If there are harness routing issues or nearby heat sources, verify insulation integrity.

3) Electrical tests for injector 6 circuit

• Resistance test: With the ignition off, measure the injector coil resistance of cylinder 6 and compare to the OEM/spec value in the service data. An open or significantly high resistance indicates an injector coil problem or internal open circuit.
• Continuity test: Check for continuity from the injector connector pin to the injector itself and to the ground/return path as applicable in the vehicle's circuit diagram.
• Signal test (noid light or scope): With ignition on and engine cranking, observe the injector drive signal to cylinder 6:
  • If using a noid light: The light should flash with crank/no-start cycles, indicating PCM is sending a pulse to the injector.
  • If using a scope: You should see a clean, repeating duty-cycle signal when the engine runs; inconsistent or absent pulses point to wiring, connector, or PCM-drive issues.

4) Compare injector 6 to other injectors (swap or cross-check)

• Swap test: If possible, move cylinder 6 injector to another cylinder (or install a known-good injector in cylinder 6) and observe if the P0206 code moves with the injector or remains on cylinder 6:
  • If the code moves with the injector, the injector is likely faulty (or its pinout/coil is the issue).
  • If the code stays on cylinder 6, the problem is likely in the wiring, connector, or PCM driver channel for cylinder 6.

5) Fuel system considerations

• Fuel pressure test: With system under spec, verify rail pressure is within the manufacturer's specification. Low pressure can cause injector performance issues and misfires even if the injector itself is electrically healthy.
• Check for rail contaminant or clogging signs (rare but possible) if symptoms are intermittent and correlate with fuel quality.

6) PCM/injector-driver assessment

• If injector 6 shows proper resistance and proper supply signal is confirmed, but the injector does not actuate or the drive signal is not consistent, consider PCM or injector-driver circuit fault.
• If all other injectors operate normally, but cylinder 6 has an isolated issue, PCM channel fault is more plausible than injector coil fault.

7) Post-repair verification

• Clear DTCs and perform a test drive to confirm the issue does not return; monitor live data for injector 6 activity and cylinder misfire counters.
• Re-test fuel pressure and injector signal to ensure stable operation after repair.
• If symptoms persist after all above checks and replacements, revisit step 3 and consider alternate root causes (e.g., a secondary air or ignition-related issue contributing to misfire, or a more complex PCM issue).

Test/result interpretation guide

• Injector 6 coil resistance out of spec or open circuit: Replace injector 6 or repair coil; recheck the circuit once replaced.
• No injector drive signal to cylinder 6: Inspect wiring/connectors; test PCM driver; potential PCM replacement if wiring and injector coil are sound.
• Injector 6 signal present but no measurable fuel delivery (e.g., swapping injector confirms misfire follows injector): Replace injector 6 and recheck.
• Normal injector coil resistance and normal drive signal but persistent misfire and P0206 persists: Re-examine rail fuel pressure, possible injector scrubbing/contamination, or PCM-related fault; consider additional tests or service manual guidance.

Documentation

• P0206 is typically a fuel injector circuit issue for cylinder 6. The most likely root cause is the injector itself or its wiring, but the exact fault could be the injector, the harness/connector, or the PCM driver for that injector. This aligns with common patterns noted in the OBD-II trouble-code framework (powertrain codes) and the specific cylinder 6 injector open-circuit reference found in the open-source injector-definition entry.
• A proper fix should include verifying wiring and the injector's electrical behavior, then replacing the faulty component with a tested part, followed by re-testing to ensure the code does not return.

This diagnostic guide was generated using verified reference data:

• Wikipedia Technical Articles: OBD-II
• Open-Source OBD2 Data: N/A (MIT)

Content synthesized from these sources to provide accurate, real-world diagnostic guidance.

---