Comprehensive diagnostic guide for OBD-II code P0260

Summary of P0260

• Likely related to an intermittent fault in the injector control signal (Injector Circuit / injector signal to the PCM). Some OEMs label cylinder- or bank-specific injector circuit faults, while others may describe intermittent injector control signals. Because do not give a single universal OEM definition for P0260, treat P0260 as an injector-circuit/intermittent-signal issue that can involve wiring, connectors, injector(s), the injector-driver output from the PCM, or related power/ground integrity. This is consistent with the general concept of injector-circuit DTCs described in the Wikipedia OBD-II sections and the open-source interpretation provided.

Symptoms

• Check Engine Light (CEL) or MIL illuminated, often intermittently as the signal fails or resumes.
• Rough idle, misfire-like behavior, or stumble when the injector signal drops out intermittently.
• Engine hesitation or reduced power under load, particularly when the affected injector signal is intermittent.
• Poor fuel economy or uneven fuel-trim readings when the fault is active.
• In some cases, engine may run normally at times and then exhibit roughness or stumble as the signal becomes intermittent.

Note: Real-world symptom descriptions can vary by vehicle and by which injector/cylinder is affected. The above reflects typical injector-intermittent-signal complaints aligned with the general DTC family discussed .

Diagnostic Approach

1) Confirm the fault and gather data

• Use a scan tool to confirm P0260 is present and note any related codes (e.g., P03xx misfire codes, P0261-P0264 for other cylinders, fuel-trim codes, or fuel-pressure codes).
• Review freeze-frame data and pending codes, if available. Look for patterns (engine load, RPM, temperature) when the code was stored.
• If the vehicle has more than one fuel-injection channel, determine if the fault is isolated to a specific injector/cylinder or appears to be multi-cylinder.

2) Initial physical and electrical inspection

• Visually inspect wiring harnesses and connectors to the injector(s) and to the injector-driver circuit in the PCM:
  • Look for damaged insulation, cracked loom, chafed wires, or signs of heat/shorts.
  • Check for loose, corroded, or bent pins in the injector connectors.
• Inspect the injector power supply and grounding:
  • Ensure proper battery voltage supply to the PCM and injector drivers; verify clean, solid ground paths.
• If there are multiple injectors, note whether the symptom or code tends to be associated with a specific injector or if it seems intermittent across the bank.

3) Electrical signal testing (injector signal/intermittent nature)

• Use a noid light or an oscilloscope to observe the injector "on/off" signal from the PCM:
  • A noid light test confirms the PCM is sending injector drive pulses to the injector(s) on demand, but it may not reveal intermittent timing issues or voltage drop when the fault occurs.
  • An oscilloscope or advanced scan data can show waveform integrity, duty cycle, pulse width, and any intermittent drops in signal.
• If available, monitor injector duty cycle and injector on-time in live data during a suspected fault. Look for:
  • Inconsistent duty cycle or irregular pulse width when the code is active.
  • A loss of signal (no pulse) or wide variations in on-time that correlate with the misfire-like symptoms.

4) Injector resistance/functional checks

• Measure the electrical resistance of each injector coil (at room temperature) and compare to the manufacturer's specification for that injector or cylinder. Known deviations may indicate a weak or failing injector.
• If you have a dynamic test method, perform a controlled injector balance or bezel test (swap/injector-bypass-type tests as applicable to the vehicle) to see if the fault follows a particular injector or remains on the same cylinder.

5) Fuel-system considerations

• Check fuel pressure and flow:
  • A significant drop in fuel pressure can amplify symptoms of injector issues and cause misfires or irregular operation that resemble an injector signal problem.
  • Replace or service the fuel filter if restricted flow is suspected.
• If fuel supply is suspect, verify that the fuel pump and pressure regulator are delivering consistent pressure over the operating range.

6) Mechanical/PCM considerations

• If electrical tests and injector testing do not isolate a failed injector or wiring issue, consider the PCM injector-driver circuit:
  • Inspect PCM power and ground pins; voltage rails must be stable and within spec.
  • Review any vehicle-specific service bulletins (TSBs) that address injector-driver or injector signal intermittency; software calibration updates can affect injector timing and signal integrity.
• In rare cases, a failing PCM or injector-driver module can be the root cause of intermittent injector signals.

7) Diagnostic confirmation and verification

• If a specific injector and its wiring are found to be marginal or damaged, repair/replace the injector, wiring harness, or connector as required.
• If the injector signal intermittency persists after hardware repair, re-check for other contributing factors (e.g., high resistance in wiring, intermittent grounding, or a software-related issue in the PCM).
• Clear codes and perform a road test or drive cycle to verify that P0260 does not return and that no new codes appear.

8) Post-repair verification

• After repair, re-scan for codes and review freeze-frame data to confirm transient conditions are resolved.
• Re-test with oscilloscope/noid-light tool to confirm stable injector signals under load and during varying RPM/engine loads.
• Confirm fuel trims converge to normal ranges and that misfire-related codes (if any) are cleared and do not reappear.

Probable Causes

• Wiring/connectors to injector or injector-driver wiring faults (intermittent contact, chafing, corrosion): 35-50%
• Faulty injector(s) or injector coil (internal open/short, stuck-open/stuck-closed intermittently): 15-25%
• PCM injector-driver output or related control circuitry issues: 10-20%
• Low or unstable fuel pressure/ fuel supply side contributing to intermittent injector operation: 5-15%
• Other (short to ground, parasitic draws, software/ calibration issues): 5-10%

Important Notes

• The general concept of DTCs and their role in monitoring parameters is described in Wikipedia's OBD-II sections on Diagnostic Trouble Codes and Powertrain Codes, which establish that modern systems monitor various parameters and generate codes when issues are detected. Citations: Wikipedia - OBD-II: Diagnostic Trouble Codes; Wikipedia - OBD-II: Powertrain Codes.
• Use of these sources means the diagnostic guide emphasizes injector-circuit/intermittent-signal possibilities and the corresponding diagnostic steps. OEM terminology and exact code wording can vary, so adapt the interpretation to the vehicle's service information and scan data.

Safety Considerations

• Disconnect battery only with ignition off and follow proper procedures when working near fuel lines or electrical connectors.
• Depressurize the fuel system safely if you plan to remove fuel lines or injectors.
• Use appropriate PPE; avoid shorting electrical circuits or creating fire hazards when testing ignition and fuel systems.
• When working on high-pressure fuel systems, follow manufacturer procedures and isolation methods.

Tools Needed

• OBD-II scan tool capable of live data and freeze-frame retrieval
• Noid light (injector signal test) or oscilloscope for injector pulse waveform
• Multimeter for resistance checks and continuity tests
• Fuel pressure gauge (specifically for the fuel rail)
• Reference values for injector coil resistance and fuel pressure for the vehicle being serviced (from service data)
• Optional: Fuel-injector balance/test equipment or injector swapping tools for diagnostic follow-up

Documentation

• Record all findings, including injector resistances, wiring checks, fuel-pressure readings, and waveform observations.
• Document the exact cylinder/injector affected (if identifiable) and the steps taken to verify or refute it.
• After repair, re-scan for codes and verify that P0260 does not reappear on the road test.

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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