Common problems · 2003–09
4th Gen 4Runner problems: 8 things to check
The problems owners and specialists flag most on the Toyota 4Runner 4th Gen, the repairs they end up doing and what those cost, plus the years and recalls to watch. Sourced, not scraped.
4th Gen 4Runner problems to check before you buy
- Frame rustNot as notorious as contemporary Tacomas, but salt-belt trucks rot. Inspect the rails, crossmembers and rear suspension link mounts with a hammer and a light — and note the 4Runner wasn't part of Toyota's Tacoma/Tundra/Sequoia frame programmes.
- V8 air-injection pump and manifoldsCarComplaints owners report the V8's secondary air injection system failing around 100,000–150,000 miles, triggering a check-engine light and limp mode, with $2,000–4,000 repair bills. Cold-start ticking can be a leaking exhaust manifold, which on the V8 is integrated with the catalytic converters.
- V8 timing belt recordsThe 2UZ-FE has a timing belt (the V6 has a chain). Toyota's maintenance guide lists replacement at 90,000 miles or 108 months (as summarised by Cherish Your Car); LC Engineering suggests inspecting from about 60,000 and doing the water pump at the same time. No records means budget for it.
- V6 coolant loss2003–05 V6s are the ones Autotrader says report head-gasket failures more than average, and forum owners point to 2003–04 in particular; a cylinder 6 misfire (P0306) plus coolant loss is the red flag. Check the overflow level, watch a cold start, and consider a combustion-gas test.
- X-REAS and rear air springsX-REAS shocks leak and rust with age and TacomaWorld members note they're replaced in pairs at real cost. On Limiteds with rear height control, check the rear doesn't sag overnight. Either can be converted to conventional parts.
- Brake actuatorListen with the engine running: a TacomaWorld member found the ABS accumulator pump cycling every 30 seconds with pedal vibration on one test truck — a sign the actuator is on its way out.
- Steering, CVs and bushingsTurn to full lock and look for a wet inner rack boot (fluid seeping into it damages the inner joint), torn CV boots past 100,000 miles, and clunky front sway-bar bushings.
- Dash and interiorCracked dashboards were common enough that Toyota's ZE6 warranty enhancement covered 2003–2005 4Runners, but that coverage has long since lapsed. Check that the third-row seat, power rear window and interior lights all work.
The repairs 4th Gen 4Runner owners end up doing
| REPAIR | SYMPTOMS | DIFFICULTY | TIME | COST |
|---|---|---|---|---|
| Replace X-REAS with conventional shocks | Leaking or rusty X-REAS shocks, a floaty or wallowy ride, a quote for four OEM units that's more than the truck feels worth. | 3 / 5 | A day | Bilstein 5100 four-shock set with front mounts ≈ $650 (ShockWarehouse) |
| Rear air suspension to coil conversion (Limited) | Rear sagging after sitting, a compressor running constantly, a height-control warning on the dash. | 2 / 5 | An afternoon | Conversion kit plus coil springs |
| Differential and transfer case fluid service | Unknown service history, whining diffs, a 4WD system that's never been exercised. | 1 / 5 | A short afternoon | Gear oil ≈ $5–15 a quart plus crush washers |
| Front wheel bearing / hub assembly | A hum or growl that changes with speed, play in the front wheel, an ABS light. | 2 / 5 | An afternoon | Hub assembly plus labor |
| Radiator replacement and external trans cooler (V6) | Coolant weeping from the bottom of the radiator — the driver's-side bottom is a common failure point on 4th gen V6s — or an old original radiator you don't trust with transmission cooling. | 2 / 5 | An afternoon | Aftermarket radiator ≈ $134 and trans cooler ≈ $39 (2014 prices quoted on 4Runners.com) |
| 2UZ-FE timing belt and water pump (V8) | Due by mileage or age, no records, a weeping water pump. A failed belt can do severe engine damage, per LC Engineering. | 4 / 5 | A full day for most | LC Engineering 2UZ belt kit ≈ $145, plus water pump |
| VSC / TRAC light zero-point calibration | VSC, TRAC or TRAC OFF lights that stay on after a battery change, alignment, sensor work or a fluid service — with no actual fault. | 1 / 5 | Minutes | Free |
Each repair links to a step-by-step guide with tools, part numbers and where to buy the parts.
Years with known problems
| YEARS | FLAG | WHAT TO KNOW |
|---|---|---|
| 2003–05 | Beware | V6 head gaskets: Autotrader says failures on 2003–05 V6s are reported more than average, and Expedition Portal owners put most of them in 2003–04. Wikipedia dates the revised gasket to late in the 2006 model year |
Every 4th Gen 4Runner model year, with the best ones to buy →
4th Gen 4Runner recalls and service bulletins
- Fuel pulsation damper leak (V6) ↗ 2003 · NHTSA 03V-146Improperly assembled damper on the fuel rail can tear its diaphragm and leak fuel.
- Port-installed alloy wheel upgrade ↗ 2003 · NHTSA 02V-339Some trucks fitted with a four-wheel alloy upgrade at the Jacksonville, FL port.
- Floor mat pedal entrapment ↗ 2003–2009 · NHTSA 11V-113An unsecured or incompatible driver's mat can trap the accelerator pedal wide open.
- Side curtain airbag inadvertent deployment ↗ 2004–2006 · NHTSA 16V-065Airbag control module may be programmed so curtain airbags deploy unexpectedly.
- Cracked, sticky or melted dashboard — warranty enhancement ↗ · ZE6Covered certain 2003–2005 4Runners for 10 years from first delivery; long expired.
Check any VIN for open recalls at nhtsa.gov/recalls ↗, or see the recall tracker.
Take the printable 4th Gen 4Runner inspection checklist: every check on this page plus the model-specific ones, on one sheet. Get the checklist →
Sourced from owners, specialists and factory documents; full sources are on the 4th Gen 4Runner guide. Verify torque figures and procedures against the factory service manual (disclaimer).