What P0121 Means on a 2022 Infiniti QX80
A P0121 on your 2022 Infiniti QX80 means the ECM has flagged an abnormal throttle position sensor pattern. The voltage is within limits but doesn't correlate with your pedal position—our detective has spotted an inconsistency in the throttle body's communication.
The 2022 QX80 uses the 5.6L V8 (VK56VD) with Nissan's VVEL (Variable Valve Event and Lift) and direct injection, producing 400 hp. This naturally aspirated DI V8 is unique in the luxury SUV segment. The large-displacement engine has a big throttle body that moves substantial airflow.
Symptoms
- Check engine light on
- Hesitation during acceleration, especially when loaded
- Idle roughness
- Throttle response delay
- V8 may not feel as smooth as expected
Causes Ranked
- Carbon buildup on throttle body – The VK56VD's direct injection deposits carbon on the throttle plate. The QX80's use for towing and hauling increases engine load and deposit formation. Likelihood: 45%
- Throttle body assembly wear – The large V8 throttle body's TPS or motor can develop issues at this age. Likelihood: 25%
- VVEL system interaction – The variable valve event and lift system interacts closely with throttle control. A VVEL actuator issue can create TPS-like symptoms. Likelihood: 15%
- Wiring or connector issue – Engine bay heat degradation. Likelihood: 10%
- Intake air leak – Cracked intake duct or loose clamp. Likelihood: 5%
Repair Costs
- Throttle body cleaning: $120–$200 (shop) / $10–$25 (DIY)
- Throttle body replacement: $400–$700 parts and labor
- VVEL actuator repair: $500–$1,200
- Wiring repair: $100–$300
Warranty
Your 2022 QX80 should be within Infiniti's 4-year/60,000-mile basic warranty depending on mileage. The 6-year/70,000-mile powertrain warranty should apply. Contact your Infiniti dealer for a no-cost diagnostic using Consult-III+.
How AutoDetective AI Can Help
AutoDetective's AI understands the VK56VD engine's unique VVEL and DI characteristics. Upload your scan data for a diagnosis that accounts for the V8's specific failure patterns.