P0351 Toyota Highlander
Ignition Coil A Primary/Secondary Circuit Malfunction · Powertrain Code · High · Repair: Easy
What is P0351?
The ignition coil for cylinder 1 has an electrical fault.
When the Toyota Highlander triggers code P0351 (ignition coil a primary/secondary circuit malfunction), it typically points to an issue in the powertrain system. This is a high severity code, so address it promptly to avoid further damage or safety concerns. Below you'll find the most common causes, symptoms, and repair options specific to the Toyota Highlander.
This repair is rated easy, meaning basic tools, no lift needed.
Diagnostic data on this page is compiled from publicly available repair resources and technical service bulletins. Always have a qualified mechanic confirm the diagnosis before authorizing repairs on your Toyota Highlander.
Common Causes on Toyota Highlander
- Ignition coil 1 primary or secondary circuit failure
- Failed Denso coil-on-plug unit for cylinder 1 (Denso 90919-02258 or similar)
- Damaged coil connector or corroded pins
- ECM driver circuit failure for coil 1 (rare)
Symptoms
- Check Engine Light on, possibly flashing
- Cylinder 1 misfire with rough idle
- Loss of power and vibration
- Strong fuel smell from unburned fuel
Notes for Toyota Highlander
Toyota Denso coil-on-plug units are reliable but do fail after 100k+ miles — when replacing one, consider replacing all coils as preventive maintenance.