Checks, in order
- Gas capTighten until it clicks and inspect the rubber seal. Clear the code and see if it stays off over a few days of driving.easy $ · under about $50
- EVAP hoses and filler neckLook at the lines near the tank, canister and filler neck for cracks. Rust on the filler neck on older trucks can also cause a leak.medium $ · under about $50
- Purge valve and vent valveA purge valve stuck open can cause rough idle after fueling. Check them for sticking and for the correct click when energized.medium $$ · about $50 to $500
- Exhaust leak before the converterA leak ahead of the downstream sensor can trigger a P0420 on its own. Listen for ticking and look for black soot at joints.medium $$ · about $50 to $500
- Catalyst efficiencyWatch the upstream and downstream air-fuel/oxygen sensor traces on a scan tool. The downstream signal should be steadier than the upstream. If it mirrors it, the converter is worn out.hard $$$ · shop-level job, $500+
Applies to: US-market FJ Cruiser, 2007 to 2014, with the 1GR-FE 4.0L V6 (timing chain) and either the 5-speed automatic or the 6-speed manual. Assumes the part-time 4WD model with a floor-mounted transfer case lever; 2WD trucks skip the 4WD checks.
Tools and parts for these checks
Links below are affiliate links: toyotadata earns a commission from VEVOR and, as an Amazon Associate, from qualifying Amazon 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 |
| Gas cap for your truck | The most common EVAP leak fix | Shop on Amazon |
| EVAP smoke leak detector, 12V | Finding the leak in the EVAP system | Shop on VEVOR |
| Downstream oxygen sensor | Replacing a lazy rear O2 sensor before condemning the converter | Shop on Amazon |
More FJ Cruiser problems
- Rust on the frame, especially at the rear crossmember (Frame & Body)
- Clunk or thump from the rear when coming to a stop or pulling away (Drivetrain)
- Steering wheel shimmy or flutter at highway speed (Steering & Suspension)
- Vibration that changes with vehicle speed, felt in the seat or floor (Drivetrain)
- Oil leaking from the rear differential, or whining, howling or grinding from the rear axle (Drivetrain)
- 4WD will not engage, or the A-TRAC / VSC lights come on (Drivetrain)
All 16 FJ Cruiser 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.