5th Gen 4Runner: Rough idle, shaking, or misfire with a flashing check engine light

Checks, in order

1. Scan for the cylinder
   A basic OBD2 reader will show P0301 to P0306 for the misfiring cylinder, or P0300 for random. Cylinders 1, 3, 5 are one bank and 2, 4, 6 the other, which helps narrow it down.
   easy $ · under about $50
2. Spark plugs
   Pull the plugs and check the gap and condition. High-mileage trucks past the service interval are a common fix, and iridium plugs are the normal type here.
   medium $ · under about $50
3. Swap coils between cylinders
   Move the coil from the misfiring cylinder to another one and clear the code. If the misfire follows the coil, replace that coil.
   easy $$ · about $50 to $500
4. Look for oil in the plug wells
   While the coils are out, check the tubes for oil. A leaking tube seal will foul the plug and boot and cause repeat misfires until it is resealed.
   medium $$ · about $50 to $500
5. Vacuum leaks and fuel delivery
   Listen for hissing, inspect the intake boot and brake booster hose, and note if the idle changes with the hood open. If every cylinder is affected, test fuel pressure before blaming the ignition.
   medium $$ · about $50 to $500

Applies to: 5th generation 4Runner, 2010 to 2024, with the 1GR-FE 4.0L V6 and the 5-speed automatic. Assumes the stock configuration; trim-specific items (KDSS, sunroof, A/C) are noted where they apply.

Tools and parts for these checks

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Go deeper

• Toyota 1GR-FE 4.0 V6 Engine Guide: Specs, Problems & Reliability

The same problem on other Toyotas

• 4th Gen Tacoma (2024–present): Rough idle, misfire or shaking at a stop
• 3rd Gen Tacoma (2016–2023): Rough idle, shaking at a stop or misfire (P0300 to P0306)
• 1st Gen Tacoma (1995.5–2004): Rough idle, misfire or lean codes (P0171, P0174, P0300)
• 4th Gen 4Runner (2003–2009): Rough idle, misfire or hesitation
• FJ Cruiser (2007–2014): Rough idle, stumbling or a misfire code (P0300 to P0306)
• 100 Series Land Cruiser / Lexus LX 470 (1998–2007): Rough idle, stumbling or a misfire code (P0300 to P0308)

Other fuel & ignition problems on the 5th Gen 4Runner

• Check engine light with P0171 or P0174, system too lean
• Engine cranks but won't start

More 5th Gen 4Runner problems

• Rust on the frame, flaking, or holes in the frame rails (Frame & Body)
• KDSS warning, fluid leak, or clunking and uneven ride on a KDSS truck (Steering & Suspension)
• Oil leak or oil smell from the front of the engine (Engine)
• Check engine light with P0420 or P0430, catalyst efficiency (Emissions)
• Temperature gauge climbing, coolant loss, or overheating (Cooling)
• Turn the key: click or nothing, engine won't crank (Starting & Charging)

All 16 5th Gen 4Runner symptoms in the interactive troubleshooter →

General guidance from owner experience. Confirm torque specs, fluid capacities and procedures in the factory service manual. Brakes, steering and anything structural: if in doubt, have a qualified shop inspect it before driving.