What Does P0122 Mean on a 2023 Honda Civic?
A P0122 code on your 2023 Honda Civic is a serious throttle system alert. Unlike P0121 (erratic signal), P0122 means the ECM has detected that the throttle position sensor voltage has dropped below the minimum threshold—approximately 0.2 volts. Think of it as a detective's key surveillance camera going completely dark rather than just showing fuzzy images. This is a circuit failure, not a performance issue.
The 2023 Civic (11th generation) uses a 2.0L naturally aspirated four-cylinder or a 1.5L VTEC turbocharged four-cylinder with direct injection. Both feature Honda's drive-by-wire electronic throttle control with dual TPS signals integrated into the throttle body assembly.
Symptoms: More Severe Than P0121
- Check engine light on—often accompanied by additional TPS codes
- Severe loss of throttle response or complete throttle failure
- Engine may default to a fixed idle speed and refuse to accelerate
- Harsh limp mode with very limited RPM and speed
- Engine may stall unexpectedly
Top Causes: This Is an Electrical Problem
- Corroded or damaged throttle body connector – Bent pins, moisture intrusion, or oxidized contacts cause the TPS signal to drop below threshold. Likelihood: 35%
- Failed throttle body assembly – The internal TPS sensor has shorted to ground or developed an open circuit. Likelihood: 30%
- Wiring harness damage – A cut, chafed, or pinched wire in the TPS circuit between the throttle body and ECM. Likelihood: 20%
- ECM 5V reference voltage issue – The reference signal from the ECM to the TPS is compromised, possibly shared with other sensors. Likelihood: 10%
- Water intrusion – Moisture from engine washing or heavy rain entering the connector. Likelihood: 5%
Estimated Repair Costs
- Connector cleaning/repair: $50–$150
- Throttle body replacement: $300–$500 parts and labor
- Wiring harness repair: $150–$350
- ECM diagnosis/repair: $200–$500+
This Needs Immediate Attention
Your 2023 Civic is within Honda's 3-year/36,000-mile basic warranty and 5-year/60,000-mile powertrain warranty. P0122 is more urgent than P0121—potential throttle failure makes this a safety concern. Take it to your Honda dealer immediately. The dealer will use Honda Diagnostic System (HDS) to check TPS circuit voltage, 5V reference integrity, and ground connections.
How AutoDetective AI Can Help
Upload your scan data to AutoDetective for a free diagnosis. Our AI distinguishes between circuit faults like P0122 and performance issues like P0121 to guide you toward the correct repair.