What Does P0350 Mean?
The ECM has detected a general malfunction in the primary or secondary circuit of one or more ignition coils, but cannot identify the specific coil. This code is typically set on older waste-spark or distributor-based ignition systems where individual coil identification is not supported. The fault can range from a complete coil failure to a wiring issue in the shared ignition coil power supply or trigger circuit.
Common Causes
35%
Failed ignition coil pack with cracked housing, internal winding short, or open primary/secondary circuit
25%
Faulty ignition coil driver circuit in the ignition control module (ICM) or ECM, unable to properly trigger coil primary windings
25%
Open or high-resistance connection in the ignition coil power supply (B+) circuit, often at the coil connector or ignition relay
15%
Damaged spark plug wires with excessive resistance or arcing to ground causing secondary circuit feedback
Diagnostic Steps
1
Measure ignition coil primary winding resistance across the two primary terminals (typical spec: 0.4-2.0 ohms depending on coil type). Also measure secondary resistance between the primary terminal and each secondary tower (typical: 6,000-15,000 ohms).
2
Verify battery voltage (12V+) at the ignition coil power supply connector with KOEO. If voltage is low or missing, check the ignition relay, fuse, and power feed wiring for opens or high resistance.
3
Using an oscilloscope with an inductive clamp on a spark plug wire, verify secondary ignition pattern shows proper firing voltage (8-15 kV), burn time (1-2 ms), and no erratic oscillations.
4
Inspect all spark plug wires for cracks, burns, or carbon tracking. Measure each wire's resistance (should be approximately 3,000-12,000 ohms per foot depending on wire type). Replace any wire exceeding specification.
5
Check the coil trigger signal from the ECM or ICM using a labscope. Verify a clean 0-12V square wave signal at each coil trigger terminal during cranking.
Estimated Repair Cost
$100 - $450
Parts + labor, varies by vehicle and location
The ECM has detected a general malfunction in the primary or secondary circuit of one or more ignition coils, but cannot identify the specific coil. This code is typically set on older waste-spark or distributor-based ignition systems where individual coil identification is not supported. The fault ...
The most common cause of P0350 (Ignition Coil Primary/Secondary Circuit Malfunction) is: Failed ignition coil pack with cracked housing, internal winding short, or open primary/secondary circuit
Typical repair costs for P0350 range from $100 to $450, depending on the vehicle, location, and whether you do it yourself or go to a shop.
An ignition coil circuit malfunction causes misfires that can result in loss of power during acceleration, rough idle, and catalytic converter damage from unburned fuel. Sustained driving with ignition faults risks overheating the catalytic converter.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to P0350 to identify the root cause.
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Quick Info
Category
Powertrain
System
Ignition System
Difficulty
Type
Generic (SAE)
Recommended Tools
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