P0352
Ignition Coil B Primary/Secondary Circuit MalfunctionP0352 is a generic OBD-II powertrain diagnostic trouble code: Ignition Coil B Primary/Secondary Circuit Malfunction. It is logged by the engine control unit when the powertrain monitor detects that a specific fault threshold has been exceeded — typically resulting in the malfunction-indicator lamp (MIL / check-engine light) being illuminated.
What P0352 means
P0352 is stored when the PCM/ECM detects an electrical fault in the primary or secondary circuit of ignition coil "B" — the coil associated with cylinder 2 in most firing-order conventions, though the exact cylinder assignment varies by manufacturer. The code covers both the primary side (low-voltage control circuit between the PCM and the coil) and the secondary side (high-voltage circuit between the coil and the spark plug), because the PCM can only monitor the coil driver return signal and infers secondary faults from abnormal primary behaviour.
Modern coil-on-plug (COP) and distributorless ignition systems work by having the PCM supply a constant battery voltage to the coil's positive terminal and switch the ground side (coil driver) on and off at precise intervals to control ignition timing. When the driver transistor in the PCM opens the ground, the magnetic field in the primary winding collapses and induces a high-voltage spike (typically 20,000–40,000 V) in the secondary winding, firing the spark plug. The PCM monitors the current ramp and collapse waveform on the driver circuit; deviations beyond approximately 10% from expected parameters set a code.
A P0352 fault means either the primary coil winding has an open or short, the driver circuit wire to the PCM is damaged, the coil connector is corroded or intermittent, or — less commonly — the PCM's internal coil driver transistor has failed. Secondary-side faults (cracked coil tower, failed spark plug causing excessive back-EMF) can also stress the primary circuit enough to register an anomaly. Because one cylinder is misfiring, the PCM may simultaneously log P030X misfire codes alongside P0352 and may disable the corresponding fuel injector to prevent raw fuel from entering the catalyst.
The code is generic (SAE J1979) and appears across petrol/gasoline engines from all manufacturers using individual coil-per-cylinder or wasted-spark ignition systems. Coil swap testing — moving the suspect coil to a confirmed-good cylinder and observing whether the fault follows the coil or stays on cylinder 2 — is the most efficient first diagnostic step after visual inspection.
Common causes
Most-frequently reported root causes when P0352 is logged.
-
1
Defective ignition coil B (failed primary or secondary winding)
-
2
Corroded or damaged coil B connector/wiring harness
-
3
Open or shorted primary coil driver wire between coil and PCM
-
4
Faulty or worn spark plug on cylinder 2 causing high back-EMF
-
5
Poor ground connection at the ignition coil
-
6
Moisture or water intrusion into the coil or connector
-
7
Cracked or carbon-tracked coil boot (COP design)
-
8
Failed coil driver transistor inside the PCM/ECM (rare)
-
9
Blown ignition-circuit fuse (check OEM fuse chart)
Symptoms drivers notice
How to diagnose P0352
A typical diagnostic flow when this code is present.
-
1
Connect a scan tool; record all codes (note any concurrent P030X misfire codes), freeze-frame data, and misfire counters per cylinder
-
2
Visually inspect ignition coil B, its boot or tower, connector, and surrounding wiring for cracks, carbon tracking, corrosion, burnt insulation, or moisture
-
3
Swap coil B with the coil from a confirmed-good cylinder (e.g. cylinder 1); clear codes and road-test — if P0352 follows the coil to the new position, the coil is faulty; if it stays on cylinder 2, suspect wiring or PCM
-
4
Inspect and replace the cylinder 2 spark plug if it shows excessive wear, cracking, or abnormal gap — a failing plug stresses the coil
-
5
Test battery voltage and switched power supply at the coil connector (key-on, engine-off) and verify ground continuity from the coil to chassis
-
6
Using a test light or oscilloscope, probe the coil driver/control wire at the connector with engine cranking to verify the PCM is producing the switching signal
-
7
Measure primary winding resistance with a multimeter across the coil's primary terminals; compare to OEM specification (typically 0.3–2.0 Ω for primary; secondary 6,000–30,000 Ω — consult OEM data)
-
8
If all external components test good, suspect the PCM driver circuit; consult OEM wiring diagrams and consider professional ECM testing before replacement
Related powertrain codes
Frequently asked questions
Can I drive with a P0352 code?
Only briefly and at low speeds to reach a workshop. A misfiring cylinder sends unburned fuel into the exhaust, which can destroy the catalytic converter within minutes of hard driving. The PCM may disable the injector on cylinder 2 to protect the catalyst, but this worsens drivability. Do not ignore a flashing MIL.
How do I know if the fault is the coil or the PCM driver?
The coil swap test is the most reliable method. Move the suspected coil to a different cylinder, clear codes, and drive. If the misfire and P035X code follow the coil to the new cylinder, the coil is at fault. If the code stays at cylinder 2 with a known-good coil installed, focus on the wiring harness and then the PCM driver circuit.
Should I replace the spark plug at the same time as the coil?
Yes, it is generally recommended. A failed ignition coil is often damaged initially by a worn, high-resistance spark plug, which forces the coil to work harder and generates excessive back-EMF. Replacing only the coil without addressing a marginal spark plug frequently leads to premature coil failure.
Does P0352 always mean cylinder 2 is affected?
In most common firing-order conventions, coil B corresponds to cylinder 2, but this is not universal. Some manufacturers use alphabetical coil labeling that does not align with cylinder numbering. Always verify the coil-to-cylinder mapping in the OEM wiring diagram for the specific vehicle before beginning repairs.
Can a weak battery or charging system cause P0352?
Indirectly, yes. Ignition coils require stable battery voltage to build sufficient primary current. A battery or alternator that drops voltage significantly under load can cause weak coil charging, erratic firing, and coil driver faults. Check charging system health if no obvious coil or wiring fault is found.
Disabling P0352 in software
RaceTune can permanently disable P0352 — and any other OBD-II diagnostic trouble code — on every ECU family we support. The monitor is disabled inside the ECU itself, so the fault stops being logged: the warning light stays off and the engine never enters limp mode for this code. The change is tied to your exact software version.
Software modifications affect emissions compliance and are not road-legal in many jurisdictions. RaceTune service files are intended for motorsport, off-road, and export use.
Got P0352 in your scan?
Upload your ECU file — we'll identify the exact software version and confirm whether a disable is available for your car.
Upload your file