Checks, in order
- Read codes and freeze frameUse a scan tool and note the code with engine temperature and speed. Clear it and see how fast it returns.easy $ · under about $50
- MAF sensor and air intakeClean the MAF with MAF cleaner only and check the intake tube clamps for leaks. A loose boot causes lean codes.easy $ · under about $50
- Vacuum and PCV linesInspect hoses for cracks and check the PCV valve. A leak near the intake can set P0171 or P0174.easy $ · under about $50
- Plugs and coilsA misfire code needs plugs and coil checks. Swap a suspect coil to another cylinder and see if the code follows.easy $ · under about $50
- Catalyst codesCheck for exhaust leaks before the downstream sensor and test the oxygen sensors before condemning the converter.medium $$ · about $50 to $500
Applies to: 2003 to 2009 4Runner with the 4.0L 1GR-FE V6 and the 4.7L 2UZ-FE V8, 2WD and 4WD. Engine specific items are labeled, and some issues apply mainly to early model years.
Tools and parts for these checks
Links below are Amazon affiliate links: as an Amazon Associate, toyotadata earns from qualifying purchases, at no extra cost to you. Confirm fitment for your exact truck before you order.
| ITEM | USED FOR | BUY |
|---|---|---|
| Bluetooth OBD2 scanner with live data | Reading and clearing codes and watching live sensor data | Shop on Amazon |
| Ignition coil | Swapping a suspect coil after the misfire follows it | Shop on Amazon |
| Spark plugs | Replacing worn plugs at the factory interval | Shop on Amazon |
| MAF sensor cleaner | Cleaning the mass airflow sensor | Shop on Amazon |
The same problem on other Toyotas
Other fuel & ignition problems on the 4th Gen 4Runner
More 4th Gen 4Runner problems
- V6 losing coolant, cold start misfire or overheating (early 4.0L) (Engine)
- Frame rust or rusted suspension mounts (Frame & Body)
- Clunk, knock or wandering from the front suspension (Steering & Suspension)
- Sticky, melting or cracked dashboard (Body & Electrical)
- V8 timing belt service: when is it due? (Engine)
- Ticking or diesel-like noise on cold start (Engine)
All 16 4th 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.