Comprehensive diagnostic guide for P0205: Cylinder 5 Injector Circuit Malfunction

Overview

• DTC overview: P0205 indicates a malfunction in the injector circuit for cylinder 5. In general, P020x codes cover individual fuel injector circuit issues; P0205 specifically targets cylinder 5. This interpretation aligns with OBD-II diagnostic code definitions (Powertrain Codes) and standard code naming in diagnostic references.
• Cross-check with related codes: P0205 is commonly seen with P0305 (cylinder 5 misfire) when the injector is not delivering fuel or the cylinder misfires due to lack of fuel delivery. This pairing is reflected in a real-world NHTSA complaint where P0205 and P0305 appeared together in a 2019 Chrysler Pacifica.

Symptoms and real-world observations

• MIL illumination: The Malfunction Indicator Lamp (check engine light) commonly turns on with P0205.
• Misfire symptoms: Cylinder 5 misfire can accompany P0205, often displayed as P0305 in the vehicle's memory or live data. In one real-world report, both P0205 and P0305 were present.
• Additional/related symptoms: Some owners report intermittent system indicators or warnings that feel related to electrical/fueling system behavior (e.g., intermittent display of startup/shutdown or other vehicle-system lights), though the primary diagnostic focus remains injector circuit function for cylinder 5.

Important Notes

• Functional cause concept: P0205 is associated with the injector circuit for cylinder 5. One open-source reference notes "injector cylinder 5 - open circuit" as a potential diagnostic framing for injector-related faults, underscoring that an open circuit is a plausible failure mode for injector circuits (open-circuit injector) [Open Source GitHub reference: Injetor cilindro 5 - circuito aberto].
• General OBD-II guidance: The OBD-II framework describes injector circuit faults as part of the broader set of powertrain codes and diagnostic trouble codes, reinforcing the approach of checking the electrical circuit, injector operation, and related wiring/PCM drivers when P0205 is present.

Probable root causes (with context)
Note: With only the single NHTSA complaint available for P0205, the following causes reflect both the reported case and common injector-circuit failure patterns observed in the field and in general references.

• Injector 5 circuit issue (open circuit or intermittent open): The injector coil path may be open or intermittently broken, preventing current flow or proper pulsed operation to the injector [Open Source GitHub: "injector cylinder 5 - open circuit"].
• Wiring harness/connector problem between PCM and injector 5: Damaged, corroded, loose, or overheated wiring/connectors can cause loss of signal/drive to the injector.
• Faulty injector 5 (mechanical/electrical): The injector itself can fail (sticking, clogging, or internal resistance changes) or fail to respond to PCM drive signals.
• PCM/driver (injector drive circuit) fault: Infrequent but possible-PCM injector-drive channel failure can mimic a bad injector circuit.
• Supporting fuel-system issue (less direct but impactful): Low fuel pressure or fuel-delivery issues can yield injector performance problems and misfires; however, P0205 specifically flags the injector circuit, so fuel-supply faults are typically evaluated in conjunction with injector diagnostics or additional codes.
• Other misfire interactions: When cylinder 5 misfires (P0305) and P0205 appears, the root cause could also be a combination of injector issue and related ignition or compression issues, but the primary P0205 signal points toward the injector circuit.

Diagnostic Approach

Goal: Confirm P0205 on cylinder 5, determine if the injector circuit is open/shorted or if another fault is causing the problem, and implement an appropriate repair.

1) Verify and document

• Retrieve and note all DTCs with freeze-frame data. Confirm whether P0205 appears alone or with P0305 (as in the reported case). Document engine load, RPM, temperature, and any recent maintenance events.
• Confirm symptoms and visibility of MIL; note any accompanying drivability concerns (rough idle, refusal to start, misfire hesitation, reduced power).

2) Initial electrical inspection (cylinder 5 injector circuit)

• Visually inspect the wiring harness and injector connector for cylinder 5: signs of damage, chafing, corrosion, loose connections, or oil/water intrusion.
• Re-seat the injector connector firmly; disconnect and inspect pins for corrosion or bent terminals; apply contact cleaner if needed and reseat.

injector resistance test (standalone injector check)

• With the ignition off, measure the resistance of the injector coil for cylinder 5 and compare to manufacturer specs (spec values vary by engine). A resistance that's far outside spec or an open circuit indicates a faulty injector coil.
• If possible, repeat measurement with the connector unplugged to isolate the injector from the wiring harness.

injector drive verification (live data)

• Using a scan tool or oscilloscope, observe the injector pulse signal for cylinder 5 while the engine is running. Confirm that the PCM is delivering a pulsed current/gate signal to the injector in sync with engine speed and air.
• Compare cylinder 5 injector pulse width and duty cycle to other cylinders (healthy injectors) under similar load conditions.

5) Power and grounding checks

• Verify that the injector receives proper supply voltage when the injector is commanded ON, and that the ground path through the PCM is functioning correctly.
• Check for abnormal voltage or ground bounce that could indicate wiring faults or PCM driver issues.

6) Fuel system and mechanical checks (supplementary)

• If electrical checks appear normal, test fuel rail pressure to ensure adequate fuel pressure for all cylinders. Low pressure can cause misfires even if injector circuit appears sound.
• Perform a compression check for cylinder 5 and a spark check for cylinder 5 to rule out non-fuel-related causes of misfire. Since P0205 is injector-focused, these are secondary steps if injector diagnostics are inconclusive.

7) Diagnostic testing strategies

• Injector swap test (diagnostic cross-check): Swap cylinder 5 injector with another cylinder's injector (e.g., cylinder 3) and re-check DTC and misfire distribution. If the P0305 moves to the new cylinder, the injector is the fault; if the P0205 remains on cylinder 5, wiring/PCM or circuitry may be at fault.
• Fuel-train check: If all injectors appear functional in electrical tests, verify proper fuel delivery (rail quantity, rail pressure sensor if equipped, and pump function) as support for fuel delivery consistency.

8) Safety and contamination considerations

• Relieve fuel pressure before disconnecting fuel lines or injectors; follow vehicle-specific procedures to avoid fuel spray/fire risk.
• Disconnect the battery or follow service manual safety steps when performing electrical inspections or wiring work to prevent PCM damage or accidental arcing.
• Use appropriate PPE and follow shop safety practices.

9) Repair strategies (based on findings)

• If injector 5 circuit is opened or a high-resistance fault is detected in the injector or wiring:

  • Repair/replace wiring or connectors, clean grounds, ensure proper shielding and routing, and reseat connectors.
  • Replace injector 5 if the injector coil is open, shorted, or physically damaged, and re-test.

• If wiring harness/connector faults are found (damaged insulation, corrosion), repair or replace the affected harness section and restore proper continuity.

• If PCM driver is suspected (rare):

  • Consider PCM diagnostics with service documentation; replacement/repair would typically be done by qualified service with software reprogramming if required.

• After any repair, clear codes, start the vehicle, and perform a road test or drive cycle to confirm: no DTC return and no reappearance of P0205/P0305. Re-check injector current/voltage and cylinder-specific data to verify consistent operation.

Notes on probabilities (based on available data)

• The provided NHTSA complaint set includes one reference where P0205 appeared with P0305 in a 2019 Chrysler Pacifica. This supports the general linkage between injector-circuit faults and cylinder misfire in real-world data, especially when paired with P0305.

• The described open-circuit injector condition reinforces the idea that an open circuit in injector 5 is a plausible primary failure mode for P0205 [Open Source GitHub: Injetor cilindro 5 - circuito aberto].

• Given the data, the most likely root causes are injector-circuit issues (open/short) and injector problems or connector/wiring faults. PCM-driver faults are less common but possible in edge cases.

• P0205 meaning and relation to misfire: General OBD-II/Powertrain code definitions - for the code concept and its place in the OBD-II framework.

• Real-world symptom reference: NHTSA complaint describing a case with P0205 and P0305 (2019 Chrysler Pacifica) and MIL/drive symptoms. This informs symptom patterns and co-occurring codes in the field.

• Injector fault concept (open-circuit injector potential cause): Open-source GitHub entry used to illustrate that open-circuit injector is a plausible failure mode for cylinder 5.

• Additional general context: OBD-II modules and diagnostic trouble code behavior are summarized in the same Wikipedia sections, reinforcing the approach to diagnosing injector-related DTCs within powertrain control systems.

Practical takeaway

• P0205 is a cylinder-5 injector-circuit fault. Start with a thorough electrical inspection of the injector circuit, test injector resistance, confirm PCM drive signals, and verify fuel delivery. Use the evidence from the NHTSA report (P0205 with P0305) and the injector-open-circuit concept to guide the diagnostic focus toward injector circuit integrity (wiring/connector/ injector) before attributing fault to the PCM or injector alone. After repairs, re-check with a road test and re-scan to confirm no recurrence.

This diagnostic guide was generated using verified reference data:

• NHTSA Consumer Complaints: 1 real-world reports analyzed
• Wikipedia Technical Articles: OBD-II
• Open-Source OBD2 Data: N/A (MIT)

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

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