P0301 Toyota 4Runner
Cylinder 1 Misfire Detected · Powertrain Code · High · Repair: Easy
What is P0301?
Misfire detected in cylinder 1. Typically caused by a worn spark plug, bad ignition coil, faulty fuel injector, or low compression in that cylinder.
When the Toyota 4Runner triggers code P0301 (cylinder 1 misfire detected), 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 4Runner.
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 4Runner.
Common Causes on Toyota 4Runner
- Ignition coil failure on cylinder 1 on 3.5L V6 or 2.7L 4-cylinder
- Spark plug worn from towing and heavy-load operation
- Fuel injector clogged from fuel quality issues in remote areas
- Ignition coil connector corroded from underhood moisture
Symptoms
- Rough idle with noticeable engine vibration
- Engine shaking or vibration especially at idle
- Loss of power during acceleration
- Check engine light flashing (indicating catalytic converter damage risk)
- Poor fuel economy from unburned fuel
- Unburned fuel smell from exhaust
Notes for Toyota 4Runner
Tacoma/4Runner used for towing may need earlier spark plug replacement than standard intervals.