Comprehensive diagnostic guide for OBD-II code P0208 Cylinder 8 Injector Circuit/Open

Overview

• What the code means: P0208 indicates an issue with the injector circuit for cylinder 8. In many definitions this is described as an injector circuit problem for cylinder 8, and some sources specifically note an open circuit condition (injector 8 - open circuit). This aligns with the "P0xxx" family where P0200-P0208 codes refer to individual cylinder injector circuit issues.
• How it's detected: The vehicle's on-board diagnostic system monitors injector circuit activity (voltage, current, timing) for each cylinder. When the PCM detects an abnormal condition for cylinder 8's injector circuit, it sets P0208 and typically illuminates the MIL. (Source context: Diagnostic Trouble Codes and Powertrain Codes)

Notes on definitions and potential ambiguity

• Some definitions explicitly describe P0208 as "Cylinder 8 Injector Circuit Open," while others generalize it as "Injector Circuit Malfunction." If you encounter conflicting OEM terminology, treat P0208 as the cylinder-8 injector circuit issue and verify whether the OEM uses "open circuit" vs. "malfunction" language.
• Related codes: A misfire on cylinder 8 may show up as P0308 in some vehicles; conversely, P0208 can exist without a P0308 if the injector circuit fault doesn't always produce a misfire. Always review all active codes and freeze-frame data together.

Symptoms

• MIL illuminated on or intermittently present
• Misfire feel on cylinder 8: rough idle, vibration, or hemispheric misfiring when engine is under load
• Reduced engine power or hesitation during acceleration
• Increased or abnormal fuel trim (as seen in live data) around cylinder 8
• Possible accompanying codes such as P0308 (misfire) or other injector-related codes if multiple injectors are involved

Probable Causes

Based on typical field experience, the following causes are listed in order of likelihood. Percentages are approximate and meant as a guide; actual results will vary by vehicle, market, and maintenance history.

• Injector 8 itself has an open circuit or internal fault (open/open-circuit condition in the injector coil or its winding): 40-50%
• Wiring harness or connector to injector 8 damaged, corroded, or loose (including damaged pins, poor grounding, chafing, or pin deformation): 20-30%
• Injector driver/PCM output fault or PCM fault controlling injector 8 (ECU/ECM problem or a shared driver issue affecting injector 8): 15-25%
• Fuel delivery issues affecting injector performance (fuel pressure concerns, pump, regulator, or supply rail problems that interact with injector operation): 5-10%
• Other mechanical issues in the cylinder that could masquerade as an injector circuit issue (less common spin-off effects or coincident issues): 0-5%
  Note: If sources conflict (open circuit language vs. generic injector circuit malfunction), follow the OEM's code description on the vehicle being serviced but use the above probabilities as a practical guide.

Diagnostic Approach

1) Verify and document

• Use a scan tool to confirm P0208 and review freeze-frame data: engine RPM, load, fuel trim, misfire counters, injector pulse width/duty cycle for cylinder 8, and any other injector-related data (P0200-P0208 family).
• Note any accompanying codes (P0308, P0218, P026x, P017x, etc.). MIL status, drive conditions, and any recent service history are important for context.
• Confirm the issue reproduces under the conditions noted in the freeze-frame data (cold start, idle, load, etc.).

2) Visual and safety inspection

• Degreased area around injector harness and injector connector 8; look for melted insulation, signs of overheating, corrosion, bent pins, or damaged wiring.
• Inspect the injector connector at cylinder 8 for proper seating, pin alignment, and secure locking tab. Check for fuel-soaked or damp connectors, which can cause intermittent faults.
• Ensure no fuel leaks around the injector rail, rail seals, or adjacent fuel lines-fuel leaks can create safety hazards and misdiagnosis.

3) Electrical test: injector 8 circuit continuity and resistance

• Disconnect the injector connector for cylinder 8 and inspect pin terminals for corrosion; reseat if necessary.
• Measure the injector coil resistance for cylinder 8 with the harness disconnected. Compare against the manufacturer's spec for that injector. Abnormal resistance (very high/open) indicates an internal injector fault.
• With ignition ON (engine off) check for proper voltage on the injector supply and the ground reference at the injector connector. Look for stable supply voltage and proper trigger from the PCM when the engine is cranking or running.
• If available, test continuity of the wiring from the PCM driver to the injector connector to ensure no open or high-resistance paths.
• If you find an open circuit or abnormal resistance in the injector itself, plan for injector replacement.

4) Functional test: injector pulse and operation

• Use a scan tool to monitor cylinder 8 injector pulse (duty cycle) and compare to other injectors during normal operating conditions.
• If injector 8 never receives a pulse when commanded (while other cylinders are pulsing normally), this bolsters a driver/PCM issue or wiring fault rather than a mechanical injector problem.
• If injector 8 pulses but fuel is not being properly delivered (abnormal pulse width or timing), proceed with further verification and potential injector replacement or wiring repair.

5) Injector swap test (diagnostic follow-through)

• Swap injector 8 with another cylinder's injector (e.g., cylinder 4) in the same rail and re-test with the scan tool.
• If the P0208 follows the injector (code moves to cylinder 4 after swapping), injector 8 is likely faulty and should be replaced (or the injector that was swapped in should be used as the replacement). If the same cylinder 8 continues to show the fault after swapping injectors, the issue is with the injector driver, wiring, or PCM.
• This test helps differentiate between a faulty injector vs. injector circuit/wiring/PCM fault.

6) Fuel system and related circuitry checks

• Check fuel rail pressure and regulator operation if fuel pressure test equipment is available. Abnormal pressure can create injector performance anomalies that can resemble circuit faults.
• Inspect the fuel pump, relay, and fuse circuits for proper operation, especially if multiple injectors show issues or if fuel pressure is inconsistent.

7) ECU/PCM evaluation

• If injector wiring and the injector itself prove functional and the fault persists, evaluate the PCM/driver channel for injector 8. Look for fault codes in PCM memory or intermittent outputs, and verify software/firmware status. In some cases, PCM replacement or reprogramming could be required, though this is a less common outcome.

8) Mechanical concerns to rule out

• While P0208 is an electrical/circuit concern, cylinder-related mechanical issues such as compression problems or valve-related concerns can produce symptoms that mimic injector faults. If electrical tests pass and the issue remains unresolved, perform a compression test or cylinder leak-down test on cylinder 8 to rule out mechanical faults.

Recommended repairs based on likely root causes

• If injector 8 is found open or electrically failed:
  • Replace injector 8, and re-test to confirm normal operation and that the code clears after driving and re-checking with a scan tool.
  • Inspect and repair/replace the injector wiring harness and connector if damage is found. Clean or reseat connectors as needed.
• If wiring/connector issues are found:
  • Repair or replace damaged wiring, restore good grounds, and ensure proper connector engagement. Re-test to ensure injector 8 receives the proper voltage and signal.
• If PCM/driver fault is suspected:
  • Verify software/firmware status and consider PCM reprogramming or replacement if the fault persists after wiring and injector replacement. This is less common and typically pursued after other root causes have been eliminated.
• If fuel system issues are identified:
  • Repair fuel delivery concerns (pump, relay, fuse, regulator) as needed. Ensure that injector performance is not limited by inconsistent fuel pressure.
• After any repair, clear codes and perform a drive cycle (idle, acceleration, and cruising) to verify that P0208 does not reappear. Confirm no related codes reappear and that injector 8 is operating in sync with the other cylinders.

Safety Considerations

• Relieve fuel system pressure before disconnecting any fuel lines or injector connectors.
• Work in a well-ventilated area and wear appropriate PPE.
• Avoid sparks near the fuel system; have an ABC-rated fire extinguisher accessible.
• If you suspect PCM or wiring harness failure, disconnect the battery prior to heavy electrical work and follow proper ESD precautions.

Documentation and notes for service records

• Record the exact fault code (P0208) and any related codes (e.g., P0308).

• Note freeze-frame data, injector 8 pulley, and the injector waveform or duty cycle data observed.

• Document all tests performed (resistance measurements, continuity tests, voltage at the injector connector, swap test results).

• Include repair actions taken (injector replacement, wiring harness repair, PCM software update, etc.) and any follow-up drive cycles or checks.

• General DTC concept and OBD-II framework: Wikipedia - OBD-II, Diagnostic Trouble Codes (for the concept of DTCs and how the system monitors various parameters) and Wikipedia - OBD-II, Powertrain Codes (for the relationship of P020x injector codes to cylinders). These sections provide the baseline understanding that DTCs monitor injector circuits and that P0200-P0208 are relating to individual cylinder injectors.

• Open Source definition related to Cylinder 8 injector: Injetor cilindro 8 - circuito aberto (Portuguese: Injector cylinder 8 - open circuit). This supports the notion that P0208 can be described as an open circuit in cylinder 8's injector.

• Emissions and testing context (OBD-II): Wikipedia - OBD-II Emissions Testing (context for the role of OBD-II in emissions compliance and how DTCs relate to emissions testing).

Notes

• If your OEM's documentation uses slightly different terminology (e.g., "Injector Circuit Malfunction" vs. "Open Circuit" for cylinder 8), document the exact OEM code wording and rely on the behavior described by the code (injector 8 circuit issue) rather than the phrasing alone.
• If the same cylinder code behavior is observed across multiple injectors or circuits, consider broader PCM or wiring harness concerns and review related injector bench tests and waveform data.

In summary

• P0208 is typically driven by an issue in cylinder 8's injector circuit, with open-circuit injector coils and wiring/connectors as the most common causes. A structured diagnostic approach-combining live data, electrical measurements, injector swapping tests, and fuel-system checks-will reliably identify whether the fault lies with the injector itself, the wiring/connector, the injector driver/PCM, or a fuel-delivery issue. Prioritize injector/connector testing and swapping, then expand to PCM wiring or module concerns if the fault persists. Always follow safety procedures when working with the fuel system and electrical components.

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.

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