P0121 on the All-New 2024 Infiniti QX80
A P0121 on your 2024 Infiniti QX80 signals that the ECM has detected an inconsistent throttle position sensor pattern. The data is within voltage limits but doesn't match expected behavior—our detective's first move is to investigate the electronic throttle body.
The 2024 QX80 is completely redesigned with a new 3.5L twin-turbo V6 (V35A-FTS, shared with the Lexus TX/Toyota Land Cruiser platform) producing 450 hp, replacing the previous 5.6L V8. This is a major powertrain change—the twin-turbo DI V6 has different carbon and throttle characteristics than the old naturally aspirated V8. As a first-year redesign, software calibration is a leading consideration.
Symptoms
- Check engine light on
- Hesitation during acceleration
- Turbo response feels muted
- Idle roughness
- Possible reduced power
Probable Causes
- ECM software calibration – First year on a completely new platform with a new engine. Software updates are expected. Likelihood: 40%
- Carbon deposits – The twin-turbo DI V6 can accumulate carbon quickly with city driving. Likelihood: 25%
- Throttle body defect – New platform manufacturing quality issue. Likelihood: 20%
- Connector issue – Factory assembly problem. Likelihood: 10%
- Boost system interaction – Twin-turbo wastegate or intercooler issue. Likelihood: 5%
Cost
- All repairs: $0 under warranty
- Out-of-warranty reference: Cleaning $120–$200, replacement $400–$750, software $100–$200
Dealer Visit Essential
Your 2024 QX80 is fully covered under Infiniti's 4-year/60,000-mile basic and 6-year/70,000-mile powertrain warranties. As a first-year redesign, the dealer may have specific TSBs. Take it in for free diagnosis and repair via Consult-III+.
How AutoDetective AI Can Help
AutoDetective's AI is tracking early patterns on the 2024 QX80's new twin-turbo V6. Upload your scan data for a free analysis of this new platform.