OBD codes / P0352
P0352
SeriousIgnition Coil B Primary/Secondary Circuit
A dead coil circuit means cylinder 2 dumps its unburned fuel straight into the catalytic converter, where it burns and overheats the catalyst. Keep driving to a minimum: light throttle, short distance, and a prompt repair. A flashing check-engine light is the car telling you catalyst damage is actively happening.
What this code means
P0352 reports an electrical fault in the circuit of ignition Coil B — the cylinder 2 coil on coil-on-plug engines. Each coil has a primary circuit (the low-voltage side the ECM switches to trigger the spark) and a secondary circuit (the high-voltage side that fires the plug); the ECM monitors the primary and sets this code when it sees an open or short instead of the expected electrical response. That makes P0352 fundamentally a wiring-and-coil problem rather than a worn spark plug, which fails by sparking weakly rather than by breaking the circuit. Typical causes, roughly in order of likelihood: a failed coil, a loose or corroded connector at the coil, chafed harness wiring, a blown fuse in the coil power feed, and rarely a bad driver in the ECM. Since cylinder 2 stops sparking, expect the companion misfire code P0302 alongside it.
Symptoms you might notice
- Rough idle and shaking from a cylinder 2 misfire
- Hesitation or stumble under acceleration
- Flashing check-engine light while the misfire is active
- Raw-fuel smell from the exhaust
- Reduced power and fuel economy
- Companion misfire code P0302 is common
What it costs to fix
Typical range: $60–$400 · about ~0.2–2 hrs of labor
| If the cause is… | Part | Labor |
|---|---|---|
| Ignition coil (single) | $30–$150 | ~0.2–0.5 hrs |
| Wiring or connector repair | $5–$50 | ~0.5–2 hrs |
| Spark plugs (while in there) | $20–$100 | ~0.5–1.5 hrs |
On most four-cylinder engines the coils sit right on top and a coil swap is a 15-minute job, keeping labor at the low end. Cylinder numbering varies by manufacturer, and on some V6/V8 layouts cylinder 2 can sit on the harder-to-reach bank — rear-bank coils on a transverse V6 can require intake removal and 1–3 hours of labor.
The price swings on which cause it turns out to be — so confirm the cause before paying. Diagnose P0352 for my exact vehicle →
How to fix P0352
Easy — basic tools, most owners can do this
- Inspect the connector on cylinder 2's coil
Pop the connector off coil B (cylinder 2), look inside for corrosion, oil, or spread pins, and make sure the locking tab still clicks. Cleaning the terminals and reseating the plug fixes a surprising number of these codes for free.
- Trade coil 2 with another cylinder's coil
Install coil 2 on a different cylinder, clear the code, and drive it. A P0352 that turns into a different coil-circuit code proves the coil failed; a P0352 that stays put shifts suspicion to the wiring.
- Verify voltage at the connector
Key on, back-probe the feed terminal at the coil 2 connector for battery voltage. Missing voltage sends you upstream to the fuse and harness; present voltage means the coil or its control (trigger) wire back to the computer is the issue.
- Examine the wiring run to coil 2
Check coil B's section of the harness for rub-through, heat damage near the exhaust side, or rodent chew. Repair breaks properly with solder and heat-shrink so vibration doesn't reopen the fault.
DIY or shop? The connector check and coil swap are entry-level DIY and cover the most likely causes. Voltage testing needs only a cheap multimeter. Reserve the shop for a fault you can't find in the visible wiring — an intermittent open deep in the harness or a rare ECM coil-driver failure needs a wiring diagram and a scope.
Tools for the DIY steps: OBD-II scanner · Multimeter · Socket set for coil bolts · Contact cleaner · Solder and heat-shrink tubing (for wire repair)
Not sure which step applies to your car? Get the likely cause for your exact vehicle before buying anything for P0352.
Frequently asked
Should I replace all the coils or just coil 2?
If one coil failed from age and the others share its mileage, some owners replace all of them to avoid repeat visits — that's a judgment call, not a requirement. Replacing just the confirmed-bad coil is perfectly valid, especially after a swap test proves it. Wiring or connector faults, of course, don't call for new coils at all.
What does "primary/secondary circuit" actually mean?
Each coil has two windings: the primary is the low-voltage side the engine computer switches on and off, and the secondary is the high-voltage side that actually fires the spark plug. P0352 means the computer detected an open or short in that circuit for coil B — an electrical break, not just a weak spark.
Can I keep driving with P0352?
Treat it with some urgency. A steady light and a mild stumble tolerate a careful trip to the shop; a flashing light means an active misfire is overheating the catalytic converter, so avoid load and fix it promptly.
Will P0352 fail an emissions inspection?
Yes — in areas with OBD-based testing, any active check-engine light is typically an automatic fail, and a misfiring cylinder raises tailpipe emissions on top of that. Fix the fault and let the monitors reset before testing.
Seeing P0352 on your car? Get a diagnosis specific to your exact year, make and model.
Diagnose P0352 for my vehicleSymptoms that trigger P0352
Drivers who get this code often notice one of these — each has its own likely-causes and cost guide:
Related trouble codes
Don’t have a scanner yet? A ~$25 Bluetooth adapter reads codes like P0352 from your phone — see our honest guide to the best OBD2 Bluetooth adapters.
Generic OBD-II reference. Manufacturer-specific behavior varies — confirm with a scan tool and, for safety-related codes, a professional inspection.