P0352: Ignition Coil B Primary Control Circuit/Open

What does P0352 mean?

Modern engines have one coil-on-plug ignition coil per cylinder, with the output stage either in the engine module or in the coil itself. P0352 monitors the primary control circuit of coil B – the line from the engine module to the coil or its built-in output stage – for an open circuit or high resistance. GM's module measures the voltage with its low-side driver off and flags an open circuit above 30 kΩ in 50 of 63 samples (2018 engines in the first trip, older ones after two); Ford checks continuously within 1 s, expecting a primary-current feedback for every ignition command, and shuts off injection to that cylinder for 30 s at a time. Short circuits and the secondary side have their own codes (P2300 ff). Coil B usually serves cylinder 2, but the assignment is up to the manufacturer.

The code tells you which monitor failed, not which part is broken. Test before replacing parts.

Symptoms

• Check engine light on
• Misfire and rough running on cylinder 2, often also P0302
• Loss of power, jerking under load
• Cylinder shut off (injection off), risk to the catalyst if driven on

Common causes

• High Ignition coil B faulty (output stage in the coil or primary winding open)
• High Connector at the coil corroded, loose or with a spread pin
• Medium Control, supply or ground wire open or chafed
• Low Fuse or relay of the coil supply (then usually several codes)
• Low Driver in the engine module faulty

Likelihood is a general estimate across vehicles; your make and model may differ.