What Does P0121 Mean on a 2024 Mazda CX-90?
A P0121 code on your 2024 Mazda CX-90 indicates the PCM has detected an abnormal TPS voltage pattern. On Mazda's all-new flagship three-row SUV, any engine management code deserves prompt dealer attention.
The 2024 CX-90 offers multiple powertrains: the Skyactiv-G 3.3L turbo inline-six (new engine), the e-Skyactiv PHEV (2.5L four-cylinder + electric motor), or the Skyactiv-G 3.3 turbo six with mild-hybrid (M Hybrid Boost). These new powertrains use direct injection. As a brand-new model with new engines, software calibration is the primary suspect.
Top Causes of P0121 on the 2024 CX-90
- PCM software calibration – All-new platform and engines; updates expected. Likelihood: 45%
- Factory throttle body defect – Manufacturing issue on new engine. Likelihood: 25%
- Connector assembly issue – Not properly seated. Likelihood: 15%
- Hybrid system interaction (PHEV/M Hybrid) – Torque transitions. Likelihood: 10%
- Carbon buildup – Unlikely at low mileage. Likelihood: 5%
Symptoms You May Notice
- Check Engine Light on
- Rough or inconsistent idle
- Hesitation on acceleration
- Reduced turbo boost (I6 turbo)
- PHEV: gas/electric transition may feel rough
- Cruise control issues
How Serious Is This Code?
P0121 is medium severity. Your 2024 CX-90 remains drivable. Schedule a dealer visit immediately—the all-new powertrain warrants quick attention. Full warranty applies.
Diagnostic Steps
- Take the CX-90 to your Mazda dealer—warranty covers this
- Dealer uses Mazda IDS for new-platform diagnostics
- Check for software updates for the new inline-six or PHEV system
- Inspect throttle body and connector
- Monitor TPS alongside turbo and hybrid data
Estimated Repair Costs
- Under warranty: $0 (Mazda 3-year/36,000-mile + 5-year/60,000-mile powertrain)
- PCM update: $0 under warranty
- Throttle body replacement (if out of warranty): $400–$700
Should You DIY This?
DIY feasibility is low. Your 2024 CX-90 is under full warranty and features all-new powertrains that require Mazda's latest IDS for diagnostics and calibration. Let the dealer handle everything at no cost.