Comprehensive diagnostic guide for OBD-II code P1359

What This Code Means

• Code identifier: P1359
• General meaning (as defined in the provided open-source code definitions): Ignition system spark output signal - circuit defective. In practical terms, the PCM (Powertrain Control Module) is detecting an issue with the command or the signal that drives the ignition spark output. This typically points to the ignition coil/driver circuit, wiring, or module in the ignition system.
• Context (OBD-II framework): DTCs in this family are part of Powertrain Codes monitored by the PCM. The system continuously monitors ignition control, spark output, and related circuits and sets a code when something in the ignition output path is not meeting expected parameters.

Source notes

• The general concept of DTCs and how powertrain control monitors parameters is described in Wikipedia's OBD-II sections (Diagnostic Trouble Codes, Powertrain Codes) to establish how the PCM uses trouble codes to signal abnormalities.
• The specific code definition used here aligns with the open-source entry: "Ignition system spark output signal - circuit defective".

Symptoms

• Check Engine Light (CEL) or MIL illuminated.
• Misfires or rough running, especially at idle or during acceleration.
• Hesitation or loss of power under load; inconsistent acceleration.
• In some cases, no-start or hard-start conditions if the ignition output circuit failure prevents spark.
• Ongoing or intermittent nature: the issue may come and go, causing a pending or intermittent code.

Probable Causes

Note: These likelihood estimates are informed by general field experience with ignition-signal circuit faults and are consistent with the notion that P1359 concerns the ignition output path. Exact probabilities can vary by vehicle and year.

• Most likely: Faulty ignition coil pack or individual ignition coil primary/secondary circuit failure
  • Coil internal open/short, degraded secondary winding, or mis-timed spark output can produce a defective spark output signal.
  • Typical share of P1359 cases: ~40-50%
• Wiring harness/connectors to the ignition coil(s) and related ground/power circuits
  • Damaged insulation, shorts to ground, corrosion at connectors, or loose/mis-seated connectors can interrupt or corrupt the spark output signal.
  • ~25%
• Ignition control module (ICM) or PCM output driver fault
  • The spark output is commanded by the PCM/ICM; a fault in the driver circuit or in the controlling logic can present as a faulty spark output signal.
  • ~15-20%
• Auxiliary or ancillary ignition-system issues (spark plug boots, high-tension leads on non-coil-on-plug systems, etc.)
  • If the signal is present but the spark cannot occur effectively at the plug due to boot/lead issues, a fault can appear in the output path.
  • ~5-10%
• Other / miscellaneous (timing, sensor integration, software/calibration issues)
  • Engine timing signals, crank/cam sensor discrepancies, or software calibrations can contribute to spurious ignition output readings.
  • ~5%

Important: Some OEMs map P1359 differently, and a given vehicle may show P1359 with additional ignition or misfire codes (e.g., P0300-P0308 for misfires, P035X family if a single coil is involved). The open-source definition indicates the core issue is the ignition spark output signal circuit itself.

Symptom-to-cause mapping guidance

• If P1359 appears with no other codes and no misfire data:
  • Investigate the ignition output path as a whole: coil packs, coil-to-connector harness, and PCM/ICM drivers.
• If P1359 appears alongside misfire codes (P0300-P0308) or cylinder-specific misfire codes:
  • Confirm if a particular cylinder consistently shows no spark; isolate the ignition path for that cylinder first, then check other cylinders.
• If P1359 appears intermittently or only under certain operating conditions (temp, RPM, load):
  • Pay particular attention to connector integrity, ground paths, and wiring insulation that could be affected by heat or vibration.

Recommended diagnostic plan (step-by-step)

1) Safety and preparation

• Park safely, set parking brake, and wear PPE when working near high-voltage ignition circuits.
• Disconnect battery only if you're about to perform invasive wiring checks or to safely inspect connectors; otherwise you can proceed with ignition-system tests energized, using appropriate insulation and caution.

2) Data collection and initial validation

• Retrieve and review freeze-frame data (if available) from the scan tool: look for ignition output-related data, misfire counts, RPM, load, and fuel trim.
• Note any other DTCs present (P035x, P0300-P0308, P0562/P0563 for battery/charging issues, etc.).
• Confirm whether the code is current/active or pending/historic.

3) Visual inspection

• Inspect ignition coils or coil packs, spark plug boots, and high-tension leads for damage, cracks, burns, or signs of heat.
• Inspect coil-to-connector harnesses for pin corrosion, damaged insulation, or moisture ingress.
• Check grounding points for the coil/IGN circuits and the battery negative path.

4) Electrical checks (with key off and then on as appropriate)

• Inspect the ignition coil primary and secondary resistance values against the manufacturer specifications (when available). A significant deviation can indicate a faulty coil.
• Check power supply to the ignition system (12V feed, accessory power, and ignition-switched power) and grounds at the coil/driver harness.
• Inspect for continuity and resistance through the ignition harness connectors; look for high-resistance or open circuits.
• Use back-probing or harness testing methods to verify signal presence without damaging connectors.

5) Functional/signal testing (using appropriate tools)

• If you have access to an oscilloscope or a suitable ignition waveform tester:
  • Observe the ignition primary current waveform when commanded by the PCM. A missing or irregular waveform indicates driver, coil, or signal-path issues.
  • Look for consistent, clean pulses for the coils that should be firing; an irregular or absent pulse on a coil indicates a fault in the signal path.
• If you don't have an oscilloscope, use a high-quality scan tool with ignition-signal or misfire data, and perform a cylinder-by-cylinder swap test (swap coils or coil packs where applicable) to see if the fault follows the coil.

6) Component-level checks (based on system configuration)

• Coil-on-plug (COP) or coil-pack configuration:
  • For COP: test each coil's output signal by verifying that the PCM is commanding spark to each cylinder and that the coil actually produces spark where possible. Swap a suspected coil with a known-good unit to see if the problem migrates.
  • For coil packs: perform a similar swap or separate coil testing per cylinder.
• Ignition control module or PCM:
  • If coil tests pass but P1359 persists, suspect the driver in the ICM/PCM. Look for grounding issues, power supply stability, and any PCM fault codes or software/recall service bulletins.
• Wiring and connectors:
  • Repair or replace damaged wiring, connectors, or grounds; ensure proper lock-in of connectors and pins oriented correctly.

7) Cross-check against service information and recalls

• Look for OEM service bulletins or recalls related to ignition-output signaling or ignition coil drivers; a repair may involve software updates, bulletin-driven harness revisions, or module replacement.

8) Validation after repair

• Clear DTCs and perform a road test across a range of RPM and load.
• Recheck for reoccurrence of P1359 and any related misfire codes.
• If the problem is resolved, monitor and confirm there are no new codes over time.

Key tests to perform (practical details)

• Coil primary resistance test: measure across the coil's primary terminals or specified ignition secondary ground path. Compare to OEM specs.
• Coil secondary resistance test: measure across the high-voltage terminal to the opposite end (to the spark plug boot). Compare to specs.
• Harness continuity test: test for open/short to ground or to battery; verify that the signal path is continuous and not degraded.
• Signal integrity test (if scope is available): view the commanded spark signal from PCM and the actual coil output waveform; look for timing consistency and absence of multiple pulsed signals or missing pulses.
• Jump-spark test: in some systems, you can swap coils or use a known-good coil to see if the fault follows the coil (helpful for diagnosing coil vs. driver).

How the open-source definition informs diagnosis

• The provided open-source definition centers on the ignition spark output signal circuit being defective. This points directly to the ignition coil(s), harness, and driver logic as primary areas to inspect first, before chasing other engine-management faults. It also implies that the problem may be electrical (signal path, grounding, continuity) rather than purely mechanical (timing belt/chain, valve train) unless those mechanical issues impact the ignition signal (e.g., timing faults could produce a misfire pattern that triggers the code).

Where this code fits in with other codes

• P1359 can appear alone or with related ignition misfire indicators (e.g., P0300-P0308) or coil-specific codes (P0351-P0356, depending on the vehicle). The general architecture is that P1359 flags an ignition output-signal issue, while P03xx and P035x codes help identify which component is failing or which cylinder is affected.
• OEM implementations vary; P1359 may map differently across brands/years, so always correlate with manufacturer wiring diagrams and diagnostics for the specific vehicle.

Safety Considerations

• Ignition systems involve high voltage; never probe live high-voltage circuits with bare hands or uninsulated tools.
• When performing wiring tests, use insulated PPE and follow vehicle-specific service procedures to avoid shock or short circuits.
• Disconnect the battery before performing invasive electrical harness work or connector replacement if required to avoid shorting or accidental energization.

Documentation

• Document all findings: DTCs observed, freeze-frame data, misfire counts, coil/coil-pack identification, wiring harness condition, and any service bulletin references.
• After repair, re-scan to confirm clearance of P1359 and related codes, and perform a road test to verify reliable ignition output under varied conditions.

Example diagnostic flow summary

• Start with P1359 code, confirm single-cylinder or multi-cylinder pattern, check for related codes.
• Do a thorough visual inspection of ignition components and wiring.
• Measure coil resistance and inspect power/ground supply to ignition circuits.
• Use waveform testing to verify commanded vs. actual spark output signals (with scope if available). Swap suspected coils/pack if needed to determine if the fault migrates.
• Repair/replace faulty coil, wiring harness, or ignition-driver module as identified.
• Clear codes and perform road test; verify no reoccurrence.

References

• OBD-II and DTC concept, Powertrain Codes: Wikipedia - OBD-II; Diagnostic Trouble Codes; Powertrain Codes sections (for general understanding of how DTCs are generated and monitored by PCM)
  • Wikipedia notes: modern systems use electronic controls that monitor parameters and generate trouble codes (Diagnostics and Powertrain Codes context).
• Ignition output signal fault definition: OBD2 CODE DEFINITIONS -
  • This provides the direct interpretation of P1359 as an ignition spark output signal circuit fault, guiding the diagnostic focus toward ignition coils, wiring, and the ignition-driver path.

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.

---