P0121 on Your 2022 Mitsubishi Eclipse Cross
A P0121 on your 2022 Mitsubishi Eclipse Cross means the ECM has flagged an irregular throttle position sensor signal. The voltage is in range but the pattern is off—our detective has identified a throttle body communication issue.
The 2022 Eclipse Cross uses a 1.5L turbocharged four-cylinder with direct injection producing 152 hp, paired with a CVT. This small-displacement DI turbo engine relies heavily on precise throttle control for boost management. The compact engine bay places the throttle body near turbo heat sources. The PHEV variant uses a plug-in hybrid with a different powertrain.
Symptoms
- Check engine light on
- Turbo lag or hesitation
- Rough idle
- CVT response feels jerky
- Engine feels underpowered
Causes Ranked
- Carbon buildup on throttle body – The 1.5L turbo DI engine is prone to carbon deposits. City driving and short trips accelerate accumulation. Likelihood: 50%
- Throttle body assembly issue – Internal TPS or motor degradation. Likelihood: 20%
- ECM software update – Mitsubishi calibration refinements. Likelihood: 15%
- Wiring or connector corrosion – Compact engine bay heat effects. Likelihood: 10%
- Boost system interaction – Wastegate or bypass valve. Likelihood: 5%
Repair Costs
- Throttle body cleaning: $80–$150 (shop) / $10–$20 (DIY)
- Throttle body replacement: $250–$450 parts and labor
- ECM update: $80–$150 (dealer)
- Wiring repair: $100–$200
Mitsubishi's Warranty
Your 2022 Eclipse Cross is within Mitsubishi's 5-year/60,000-mile basic warranty and 10-year/100,000-mile powertrain warranty. All P0121 repairs should be covered at no cost. The dealer uses MUT-III for diagnostics.
How AutoDetective AI Can Help
AutoDetective's AI understands the Eclipse Cross's 1.5L turbo DI platform. Upload your scan data for a free diagnosis.