P0131 on the All-New 2024 Toyota 4Runner
The 2024 4Runner is a complete redesign, moving to the TNGA-F platform with the 2.4L T24A-FTS turbocharged inline-four engine, replacing the long-running 4.0L V6. Some trims also offer a hybrid powertrain. When the new turbo engine sets P0131, the ECU has detected the Bank 1 Sensor 1 upstream O2 sensor reading persistently low voltage. Since this is an inline-four, there's only one bank — the sensor sits downstream of the turbocharger, upstream of the catalytic converter.
As a first-year production vehicle with a new engine, P0131 on the 2024 4Runner likely reflects a manufacturing or calibration issue rather than wear.
What You'll Notice
- Check engine light illuminated
- Possible reduced turbo boost response
- Subtle fuel economy decrease
- Slight idle roughness
- Emissions test failure
What's Causing the Code
1. O2 Sensor Defect
First-year production of the 4Runner's new turbo powertrain means the O2 sensor is operating in an environment that differs from previous naturally aspirated 4Runners. The turbo generates higher exhaust temperatures and different pressure pulsations. Individual sensors with marginal heating elements or sensing elements may not withstand these conditions, leading to premature low-voltage output. This is the most likely cause on a brand-new vehicle.
2. Turbo Exhaust Path Leak
The turbocharged exhaust system has multiple gasket joints — manifold to turbo housing, turbo to downpipe, and downpipe to catalytic converter. First-year production vehicles sometimes have gaskets that don't seat perfectly during initial thermal cycling. The 4Runner, designed for off-road use, subjects these joints to additional stress from vibration and flex over rough terrain, potentially accelerating gasket failure.
3. Wiring Routing or Assembly Issue
New vehicle designs sometimes have wiring harness routing issues that only become apparent in real-world use. The O2 sensor wiring near the turbo housing is exposed to extreme heat. If the harness was positioned even slightly closer to the turbo than specified, insulation can degrade rapidly. For 4Runner owners who hit the trails early, underbody impacts could also disturb freshly installed wiring.
4. ECU Calibration
New engine platforms frequently receive software updates during their first year. The T24A-FTS turbo engine's diagnostic thresholds may need refinement for the 4Runner's specific driving conditions, which include more low-speed, high-load operation than the Tacoma or Highlander using the same engine. Your dealer should check for available TSBs and calibration updates.
Repair Costs
- All warranty repairs: $0
- O2 sensor (if out of warranty): $200-$400
- Exhaust gasket repair: $250-$550
- Wiring repair: $100-$250
Take It to the Dealer
Your 2024 4Runner is fully covered under Toyota's warranty. The 3-year/36,000-mile comprehensive warranty and the federal emissions warranty (up to 8 years/80,000 miles for O2 sensors) mean you shouldn't pay anything for this repair. Don't attempt a DIY fix on a vehicle this new — you could inadvertently void warranty coverage for related components. Document everything and keep your service records.
Urgency
Schedule a dealer appointment within one to two weeks. On the turbo engine, accurate O2 sensor data is important for proper boost management, especially during off-road driving where the engine works hard at varying speeds and loads. The ECU will compensate with conservative maps, but prompt repair restores full performance and efficiency.