Comprehensive diagnostic guide for OBD-II code P0352

Ignition Coil B Primary/Secondary Circuit Malfunction

What This Code Means

• P0352 = Ignition Coil B Primary/Secondary Circuit Malfunction.
• This definition aligns with the standard OBD-II family of ignition coil codes (P0351-P0356) where the fault is in the primary/secondary circuit of the B coil. Source notes: MIT-hosted open-source OBD-II code definitions; and the OBD-II Powertrain Codes overview discusses coil-related DTCs as part of the system. See also general OBD-II powertrain code coverage in Wikipedia's OBD-II section.

Symptoms

• Check Engine light (CEL) / MIL illuminated with P0352 stored.
• Misfire symptoms on the cylinder attributed to coil B (rough running, stumble, or misfire in that cylinder).
• Intermittent loss of power or reduced engine performance; noticeable under load.
• Rough idle or engine vibration at low RPM.
• Possible secondary codes may accompany P0352 (e.g., P0302 for the misfire on cylinder B, or P0300 for random/mimbal misfire patterns).
• In some cases, no visible symptoms beyond the MIL until the vehicle is driven and the condition worsens.

Common Causes

• Ignition coil B itself (primary/secondary winding internal failure or intermittent open/short): high likelihood (roughly 40-60%). The coil's internal insulation breakdown or degraded windings commonly produce P0352.
• Wiring harness or connector issues to coil B (damaged wire, loose/cracked connector, corrosion): moderate likelihood (roughly 20-30%).
• Power supply or grounding issues to coil B (12V feed, fused supply, or grounding path): moderate likelihood (roughly 5-15%).
• PCM/control circuitry or ignition control module fault affecting coil B drive signal: lower likelihood (roughly 5-10%), often diagnosed after confirming wiring and coil integrity.
• Related misfire codes on other cylinders or a broader ignition system fault: possible, should be checked to determine if the problem is isolated to coil B or part of a multi-coil issue.

Safety Considerations

• High-voltage ignition systems can retain a stored charge; handle with care.
• Disconnect battery or ensure ignition is off before disconnecting coil connectors; avoid contact with high-voltage wiring.
• When testing with a spark tester or scope, use appropriate insulation and PPE; follow OEM safety guidelines.
• If the engine is hot, allow it to cool before applying any test probes near spark plugs or coil packs.

Tools Needed

• OBD-II scan tool capable of live data and freeze-frame data.
• Multimeter (for resistance, continuity, voltage checks).
• Spark plug/ignition coil tester or a known-good spark tester with a visual spark path.
• Optional: oscilloscope for coil primary/secondary waveforms.
• Manufacturer service information (to confirm coil primary and secondary resistance specs and wiring diagrams).
• Basic hand tools (ratchets, sockets) and reverse polarity protection if required.

Pre-diagnosis considerations

• Check for other DTCs in the P0xxx family (P0351-P0356) to determine if the issue is isolated to coil B or part of a broader ignition/PCM concern.
• Look at freeze-frame data to determine engine load, RPM, and fault mode at the time of the fault.
• Review recent service history for coil packs, ignition wiring repairs, or aftermarket harness changes.

Step-by-Step Diagnosis

1) Confirm the code and situational data

• Use a compatible scan tool to confirm P0352 is present and note any accompanying codes (P0302, P0351, P0353, etc.).
• Review freeze-frame data: engine RPM, load, temperature, misfire counts, etc.
• If the fault is intermittent, plan to reproduce under load or high-demand conditions to observe misfire behavior.

2) Visual inspection of coil B and associated wiring

• Locate coil B (per engine wiring diagram; coil B is the secondary coil for the corresponding cylinder designation per manufacturer). Inspect the coil pack/coil-on-plug assembly, connector, and wiring harness.
• Look for signs of corrosion, bent or damaged pins, frayed insulation, heat damage, oil leaks, or coolant intrusion near the coil connectors.
• Check the connector for proper latch engagement; reseat if necessary and apply dielectric grease if recommended by OEM.

3) Power supply and grounding checks

• With ignition ON, measure the 12V feed to coil B primary and ensure stable voltage. Check for voltage drop along the circuit under load.
• Verify a solid ground path for the coil B circuit. A high resistance or intermittent ground can mimic a coil fault.
• Inspect fusible links and relevant fuses that supply the ignition circuit for B coil.

4) Primary and secondary resistance testing (reference OEM specs)

• Disconnect the coil B connector and measure coil primary resistance (between the primary +12V supply and the coil ground/control input).
• Measure coil secondary resistance (between the coil output terminal to the spark plug conductor/boot or cylinder reference). Compare both measurements to OEM service specs.
• If the resistance is out of spec (way high or open circuit), the coil is suspect. If resistance is within spec but the coil still misbehaves, suspect wiring or driver signal issues.

5) Signal verification (control signal integrity)

• If you have access to an oscilloscope or the scan tool's live data, inspect the ignition control signal to coil B:
  • Look for consistent firing pulses synchronized with crank/cam signals.
  • Look for missing or irregular voltage pulses that would indicate a driver or PCM issue.
• If the coil receives sporadic or no drive signal but the primary supply is present, the problem could be the ignition control circuit/PCM rather than the coil itself.

6) Swap/test substitution (coil-to-coil swap)

• If feasible, swap coil B with a known-good coil from another cylinder (or swap with coil A if your vehicle uses a 4-coil arrangement) to see if the DTC or misfire follows the coil rather than the cylinder.
• If P0352 moves to the previously healthy cylinder location after swap, the coil is likely failing. If the fault stays with the same cylinder's wiring/PCM, focus on wiring, connectors, or PCM control.

7) Spark output check (with spark tester)

• Use a spark tester connected to the cylinder corresponding to coil B. Perform a controlled engine crank while observing spark output:
  • A strong, consistent spark indicates coil primary/secondary may be fine and the fault is elsewhere (timing, fuel, compression, or PCM drive signal intermittence).
  • No or weak spark suggests a coil or its circuit issue (primary/secondary fault, bad connector, or control signal problem).

8) Check for related coils and engine condition

• If multiple P035x codes are present, consider broader ignition or PCM issues.
• Inspect for oil/ coolant leaks that might affect coil resealing or impedance and cause intermittent faults.

9) Final assessment and decision point

• If the coil B primary/secondary circuit test fails (open/short, bad resistance, or no drive signal) and no wiring fault remains, replace coil B (and related gaskets/per O-ring seals if applicable).
• If coil tests appear fine but the driver signal or PCM output is suspect, consult OEM service information for specific diagnostic procedures on the ignition control module or PCM.

Repair Options

• Replace ignition coil B (coil-on-plug or coil pack) with a OEM-recommended unit or a proven-aftermarket equivalent.
• Repair or replace wiring harness segments or connectors compromised by damage or corrosion.
• Clean/repair grounds and supply circuits; replace blown fuses or fusible links as required.
• Reassemble, apply dielectric grease to connectors as recommended, and ensure secure connections.
• Clear P0352 and any other codes after repairs; perform a road test to verify repair success.

Post-Repair Verification

• After repairs, start the engine and verify no P0352 is present in the DTC list.
• Run the engine to normal operating temperature and perform a test drive under normal driving conditions and under acceleration to confirm stable ignition performance.
• Recheck for any linger or recurring codes; if P0352 reappears quickly, re-evaluate coil B, wiring, and control signals or consider PCM diagnosis.

Documentation notes

• Record all measured values (primary and secondary resistances, voltage supply, ground integrity, and observed ignition signals). Include the exact diagnostic steps performed and the observed outcomes.

• Note any related DTCs and the correlation between symptoms, test results, and component replacements.

• Code definition: P0352 (Ignition Coil B Primary/Secondary Circuit Malfunction) is consistent with standard OBD-II P035x coil codes. This definition is drawn from the MIT open-source OBD2 code definitions (Code: N/A; Title: Mau funcionamento do primário/secundário da bobina de ignição B). Source: MIT OBD2 definitions repository.

• Contextual background: OBD-II diagnostic trouble codes fall under the broader OBD-II framework, including powertrain codes and emissions testing discussions. Wikipedia's OBD-II sections on Diagnostic Trouble Codes and Powertrain Codes provide context that DTCs monitor various parameters and include coil-related codes as part of the powertrain category.

Notes

• Because this guide relies on general references and field experience (with limited access to vehicle-specific OEM specs ), follow OEM service information for exact electrical specifications (resistance ranges, voltage thresholds) for your vehicle model.
• If there are conflicts between sources, prioritize manufacturer OE specifications and diagnostic procedures for coil B, while using Wikipedia as a general reference for the existence and classification of ignition coil DTCs.

Cautions and best practices

• Always verify safety prior to performing electrical tests around ignition components.
• When in doubt, escalate to the OEM service information for model-specific coil B wiring diagrams and testing parameters.
• Ensure you perform a proper post-repair road test and recheck for theft-deterrent or security-related PCM resets if applicable to the vehicle.

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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