P0122 on Your 2020 Honda Civic: Urgent Investigation
A P0122 on your 2020 Honda Civic means the ECM has detected that the throttle position sensor voltage has dropped below the minimum threshold. This is a circuit fault—the TPS signal has essentially gone dead or critically low. Unlike P0121 where the signal is erratic, P0122 means the signal has collapsed. This requires immediate attention.
The 2020 Civic (10th generation) uses a 2.0L naturally aspirated four-cylinder or 1.5L VTEC turbo. At 4–6 years old, connector corrosion and wiring degradation become significant factors alongside component wear.
Symptoms
- Check engine light on
- Severe throttle response loss
- Engine may idle but won't accelerate
- Harsh limp mode
- Possible stalling
Causes: Electrical Root
- Connector corrosion – At this age, pin oxidation and moisture damage are the #1 cause. Likelihood: 35%
- Throttle body TPS failure – Internal sensor short or open circuit from age and heat cycling. Likelihood: 30%
- Wiring degradation – Heat, vibration, and age cause insulation breakdown and wire damage. Likelihood: 20%
- 5V reference voltage drop – Shared reference pulled low by another sensor or wiring fault. Likelihood: 10%
- Ground circuit problem – Poor engine-to-body ground affecting TPS circuit. Likelihood: 5%
Repair Costs
- Connector cleaning/repair: $50–$150
- Throttle body replacement: $280–$480 parts and labor
- Wiring repair: $150–$350
- Ground repair: $50–$150
Warranty & DIY
The basic warranty has expired, but the 5-year/60,000-mile powertrain warranty may still apply. The federal emissions warranty (8 years/80,000 miles) could also cover this if under 80,000 miles. Check with your Honda dealer before paying. For DIY, start by inspecting the throttle body connector for corrosion—disconnect it, clean the pins with electrical contact cleaner, apply dielectric grease, and reconnect. If the code returns, the throttle body itself likely needs replacement.
How AutoDetective AI Can Help
Upload your scan data to AutoDetective. Our AI identifies whether you're dealing with a connector issue, wiring fault, or throttle body failure based on your freeze frame data.