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.

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HOMESERVICE MANUALSTOYOTA2012PRIUS THREEREPAIR AND DIAGNOSISRESTRAINTSRESTRAINTS CONTROL SYSTEMSPRE-COLLISION SYSTEM (EXCEPT PLUG-IN) (DIAGNOSTIC CODES & CIRCUIT TESTS)PRE-COLLISION SYSTEMDTC C1A0A: FRONT RADAR SENSOR REGION CODE MISMATCHPROCEDURE

2012 Toyota Prius Three

DTC C1A0A: Front Radar Sensor Region Code Mismatch: Procedure

2012 Toyota Prius ThreeSECTION Procedure

CHECK MILLIMETER WAVE RADAR SENSOR

Using the Techstream, enter the following menus: Powertrain / Radar Cruise / Data List.

RADAR CRUISE

Tester Display	Measurement Item/Range	Normal Condition	Diagnostic Note
Country# (F Radar Sens)	Millimeter wave radar sensor country signal/JPN, NA, EURO, AUS, SAFC, OTHER, TWN, CHINA, THAI, GCC, NOFIX	Actual country code	-

Read the Data List and check the country specification information of the millimeter wave radar sensor and vehicle.

RESULT

Result	Proceed to
Country specification information for vehicle and millimeter wave radar sensor match	A
Country specification information for vehicle and millimeter wave radar sensor do not match	B

B → See step 4

A: Go to next step

REPLACE MAIN BODY ECU
1. Replace the main body ECU. Refer to REMOVAL .
NEXT: Go to next step
CHECK DTC OUTPUT (PRE-COLLISION SYSTEM)
1. Using the Techstream, enter the following menus: Body Electrical / Pre-Collision 2 / Trouble Codes.
2. Clear the DTCs. Refer to DTC CHECK / CLEAR .
3. Recheck for DTCs.
  OK
  
  DTC C1A0A is not output.
NG → See step 5

OK → END
REPLACE MILLIMETER WAVE RADAR SENSOR. Refer to REMOVAL
REPLACE DRIVING SUPPORT ECU. Refer to REMOVAL

RENDER: 1.0x

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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.