3rd Gen 4Runner: Check engine light with a common code

Checks, in order

1. Read and write down codes
   Use a scan tool. Note the code and any freeze frame data, then clear it and see how fast it returns.
   easy $ · under about $50
2. P0401 EGR flow
   Carbon often clogs the EGR passages in the intake. Clean the passages and check the EGR valve and vacuum modulator before replacing parts.
   medium $$ · about $50 to $500
3. P0325 and P0330 knock sensor
   On the 5VZ-FE the sensors sit under the intake manifold and the wiring can go brittle. Inspect the harness first and use quality sensors if replacing.
   hard $$ · about $50 to $500
4. P0420 catalyst efficiency
   Check for exhaust leaks ahead of the rear oxygen sensor and test the sensors before condemning the catalytic converter.
   medium $$ · about $50 to $500
5. Gas cap and evap
   Make sure the cap clicks tight and the seal is not cracked. This is a cheap fix for evap codes.
   easy $ · under about $50

Applies to: 1996 to 2002 4Runner with the 2.7L 3RZ-FE four-cylinder and the 3.4L 5VZ-FE V6, 2WD and 4WD, manual and automatic. Where a check only applies to one engine it says so.

Tools and parts for these checks

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The same problem on other Toyotas

• 4th Gen 4Runner (2003–2009): Check engine light with a lean, misfire or catalyst code

More 3rd Gen 4Runner problems

• Clunk, knock or loose feel in the front end over bumps (Steering & Suspension)
• Shimmy, vibration or steering wander at highway speed (Steering & Suspension)
• Frame rust, rotten rocker panels or rusty underbody (Frame & Body)
• Engine overheating or temperature gauge climbing (Cooling)
• Pink or milky transmission fluid, or coolant in the transmission (Transmission)
• 5VZ-FE timing belt service: when is it due and how do I tell? (Engine)

All 16 3rd 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.