Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
2021 Toyota Prius LE AWD-eFACTORY OEM SERVICE PROCEDURE
Dynamic Radar Cruise Control System
DYNAMIC RADAR CRUISE CONTROL SYSTEM DIAGNOSTIC TROUBLE CODE (DTC) IDENTIFICATION [11/2015 - 11/2017]
| DTC Code | Description |
|---|---|
| C1A01 | Driving Support ECU |
| C1A02 | Vehicle Information Not Obtained |
| C1A0A | Front Radar Sensor Region Code Mismatch |
| C1A10 | Front Radar Sensor |
| C1A11 | Front Radar Sensor Incorrect Axial Gap |
| C1A14 | Front Radar Sensor Beam Axis Not Adjusted |
| C1A4A | Skid Control Buzzer Circuit |
| C1A52 | Driving Support ECU Communication Abnormal |
| P0571-13 | Brake Switch "A" Circuit Open |
| P0571-62 | Brake Switch "A" Signal Compare Failure |
| P0575-04 | Cruise Control System Internal Failure |
| P0575-49 | Cruise Control Internal Electronic Failure |
| P1578-00 | Brake System |
| P1607-00 | Cruise Control Input Processor |
| P1630-81 | Communication Error from VSC to ECM Invalid Serial Data Received |
| P1631-81 | Communication Error from ECM to VSC Invalid Serial Data Received |
| U0122-87 | Lost Communication with Vehicle Dynamics Control Module Missing Message |
| U0125 | Lost Communication with Yaw Rate Sensor Module |
| U0126 | Lost Communication with Steering Angle Sensor Module |
| U0129 | Lost Communication with Brake System Control Module |
| U0235 | Lost Communication with Cruise Control Front Distance Range Sensor |
| U0293 | Lost Communication with Hybrid Vehicle Control System |
| U0293-87 | Lost Communication With Hybrid Powertrain Control Module Missing Message |
| U1104 | Lost Communication with Driving Support ECU |
| U1104-87 | Lost Communication with Driving Support ECU Missing Message |
DYNAMIC RADAR CRUISE CONTROL SYSTEM DIAGNOSTIC TROUBLE CODE (DTC) IDENTIFICATION [11/2017 - 12/2018]
| DTC Code | Description |
|---|---|
| C1A01 | Driving Support ECU |
| C1A02 | Vehicle Information Not Obtained |
| C1A0A | Front Radar Sensor Region Code Mismatch |
| C1A10 | Front Radar Sensor |
| C1A11 | Front Radar Sensor Incorrect Axial Gap |
| C1A14 | Front Radar Sensor Beam Axis Not Adjusted |
| C1A4A | Skid Control Buzzer Circuit |
| C1A52 | Driving Support ECU Communication Abnormal |
| P0571-13 | Brake Switch "A" Circuit Open |
| P0571-62 | Brake Switch "A" Signal Compare Failure |
| P0575-04 | Cruise Control System Internal Failure |
| P0575-49 | Cruise Control Internal Electronic Failure |
| P1578-00 | Brake System |
| P1607-00 | Cruise Control Input Processor |
| P1630-81 | Communication Error from VSC to ECM Invalid Serial Data Received |
| P1631-81 | Communication Error from ECM to VSC Invalid Serial Data Received |
| U0104-87 | Lost Communication with Cruise Control Module Missing Message |
| U0122-87 | Lost Communication with Vehicle Dynamics Control Module Missing Message |
| U0125 | Lost Communication with Yaw Rate Sensor Module |
| U0126 | Lost Communication with Steering Angle Sensor Module |
| U0129 | Lost Communication with Brake System Control Module |
| U0235 | Lost Communication with Cruise Control Front Distance Range Sensor |
| U0293 | Lost Communication with Hybrid Vehicle Control System |
| U0293-87 | Lost Communication With Hybrid Powertrain Control Module Missing Message |
| U1104 | Lost Communication with Driving Support ECU |
DYNAMIC RADAR CRUISE CONTROL SYSTEM DIAGNOSTIC TROUBLE CODE (DTC) IDENTIFICATION [12/2018 - 07/2020]
| DTC Code | Description |
|---|---|
| C1A01 | Driving Support ECU |
| C1A02 | Vehicle Information Not Obtained |
| C1A0A | Front Radar Sensor Region Code Mismatch |
| C1A10 | Front Radar Sensor |
| C1A11 | Front Radar Sensor Incorrect Axial Gap |
| C1A14 | Front Radar Sensor Beam Axis Not Adjusted |
| C1A52 | Driving Support ECU Communication Abnormal |
| P0571-13 | Brake Switch "A" Circuit Open |
| P0571-62 | Brake Switch "A" Signal Compare Failure |
| P0575-04 | Cruise Control System Internal Failure |
| P0575-49 | Cruise Control Internal Electronic Failure |
| P1578-00 | Brake System |
| P1607-00 | Cruise Control Input Processor |
| P1630-81 | Communication Error from VSC to ECM Invalid Serial Data Received |
| P1631-81 | Communication Error from ECM to VSC Invalid Serial Data Received |
| U0104-87 | Lost Communication with Cruise Control Module Missing Message |
| U0122-87 | Lost Communication with Vehicle Dynamics Control Module Missing Message |
| U0125 | Lost Communication with Yaw Rate Sensor Module |
| U0126 | Lost Communication with Steering Angle Sensor Module |
| U0129 | Lost Communication with Brake System Control Module |
| U0235 | Lost Communication with Cruise Control Front Distance Range Sensor |
| U0293 | Lost Communication with Hybrid Vehicle Control System |
| U0293-87 | Lost Communication With Hybrid Powertrain Control Module Missing Message |
| U1104 | Lost Communication with Driving Support ECU |
DYNAMIC RADAR CRUISE CONTROL SYSTEM DIAGNOSTIC TROUBLE CODE (DTC) IDENTIFICATION [07/2020 - ]
| DTC Code | Description |
|---|---|
| P0571-13 | Brake Switch "A" Circuit Open |
| P0571-62 | Brake Switch "A" Signal Compare Failure |
| P0575-04 | Cruise Control System Internal Failure |
| P0575-49 | Cruise Control Internal Electronic Failure |
| P1578-00 | Brake System |
| P1607-00 | Cruise Control Input Processor |
| P1630-81 | Communication Error from VSC to ECM Invalid Serial Data Received |
| P1631-81 | Communication Error from ECM to VSC Invalid Serial Data Received |
| U0104-87 | Lost Communication with Cruise Control Module Missing Message |
| U0122-87 | Lost Communication with Vehicle Dynamics Control Module Missing Message |
| U0125-87 | Lost Communication with Multi-axis Acceleration Sensor Module Missing Message |
| U0126-87 | Lost Communication with Steering Angle Sensor Module Missing Message |
| U0129-87 | Lost Communication with Brake System Control Module Missing Message |
| U0155-87 | Lost Communication with Instrument Panel Cluster (IPC) Control Module Missing Message |
| U0235-87 | Lost Communication with Cruise Control Front Distance Range Sensor Single Sensor or Center Missing Message |
| U0293-87 | Lost Communication with Hybrid/EV Powertrain Control Module Missing Message |
| U0293-87 | Lost Communication with Hybrid Powertrain Control Module Missing Message |
| U0300-51 | Internal Control Module Software Incompatibility Not Programmed |
| U0300-57 | Internal Control Module Software Incompatibility Invalid/Incompatible Software Component |
| U0318-51 | Software Incompatibility with Brake System Control Module Not Programmed |
| U0318-57 | Software Incompatibility with Brake System Control Module Invalid/Incompatible Software Component |
| U0322-51 | Software Incompatibility with Body Control Module Not Programmed |
| U0322-57 | Software Incompatibility with Body Control Module Invalid/Incompatible Software Component |
| U0594-81 | Invalid Data Received from Hybrid Powertrain Control Module Invalid Serial Data Received |
Factory Service Tools
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.
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