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 XLE AWD-eFACTORY OEM SERVICE PROCEDURE
Front Radar Sensor System
FRONT RADAR SENSOR SYSTEM DIAGNOSTIC TROUBLE CODE (DTC) IDENTIFICATION
| DTC Code | Description |
|---|---|
| C1A11-00 | Front Radar Sensor Optical Axis Misalignment Malfunction |
| C1A8C-46 | Main Microcomputer in Front Radar Sensor Calibration/Parameter Memory Failure |
| C1A8D-1C | Power Supply Circuit in Front Radar Sensor Circuit Voltage Out of Range |
| C1A90-00 | Malfunction of Millimeter-wave Circuit in Front Radar Sensor |
| C1A91-00 | Malfunction of Acceleration Sensor in Front Radar Sensor |
| U0104-87 | Lost Communication with Cruise Control Module Missing Message |
| U0305-57 | Software Incompatibility with Cruise Control Module Invalid/Incompatible Software Component |
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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