P0352: Ignition Coil "B" Primary/Secondary Circuit
The engine computer has spotted a problem in the electrical circuit for ignition coil B, usually the coil for cylinder 2.
What P0352 means
P0352 is the coil B version of the ignition coil circuit code. The engine computer turns each coil on to build up a magnetic field and off to fire the spark plug. It monitors the primary circuit while doing this, and if the signal from coil B does not match what it expects, it sets P0352. Coil B normally fires cylinder 2, though layouts vary by maker. A failing coil is the most common cause, but wiring is close behind: harnesses near hot engine parts get brittle, and connectors loosen over time. Oil leaking into the plug wells can also break down coil boots. Shops start by checking whether the code follows the coil in a swap test. If it does not, they test the power feed, ground and computer trigger signal at the coil connector. Fixing it is usually inexpensive, but driving on a dead cylinder can foul plugs and damage the catalytic converter, so do not put it off.
Common symptoms
- Check engine light, often along with P0302
- Misfire or rough idle
- Stumbling under acceleration
- Reduced power
- Fuel smell from the exhaust in bad cases
Most common causes
- Failed ignition coil B
- Open or shorted wiring between the computer and the coil
- Corroded or loose coil connector
- Coil boot damaged by oil from a valve cover leak
- Weak power or ground circuit to the coils
- Engine computer driver failure (rare)
What to check yourself first
Unplug and inspect the coil B connector for green corrosion or a broken latch. Pull the coil and check for oil in the plug well. Swap coil B with coil A and clear the code; if the code becomes P0351, the coil is bad.
Typical fixes and what they cost
| Fix | Typical cost | Note |
|---|---|---|
| Replace ignition coil | $238-$320 | Swap test first so you buy the right part. |
| Electrical diagnosis to find a wiring or connector fault | $122-$179 | For wiring or connector faults, especially when the code comes and goes over bumps. |
| Replace spark plugs | $288-$399 | Often done at the same time if plugs are worn. |
Typical US price ranges for parts and labor, not quotes. Your shop should confirm the cause with a diagnostic before replacing parts.
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Related codes
- P0351 Ignition Coil "A" Primary/Secondary Circuit
- P0302 Cylinder 2 Misfire Detected
- P0300 Random/Multiple Cylinder Misfire Detected
- P0301 Cylinder 1 Misfire Detected