2012 Toyota Prius FourFACTORY OEM SERVICE PROCEDURE

Diagnostic Trouble Code Chart

HINT:Β 

If a trouble code is stored during the DTC check, inspect the trouble areas listed for that code. For details of the code, refer to the "See" column below.

CERTIFICATION ECU (SMART KEY ECU ASSEMBLY)

DTC Code Detection Item Trouble Area See
B27A1 Open in Driver Side Electrical Antenna Circuit 1. Front door outside handle assembly (for driver side)
2. Certification ECU (smart key ECU assembly)
3. Wire harness or connector
Refer to DTC B27A1: Open in Driver Side Electrical Antenna Circuit
B27A2
*
Open in Front Passenger Side Electrical Antenna Circuit 1. Front door outside handle assembly (for front passenger side)
2. Certification ECU (smart key ECU assembly)
3. Wire harness or connector
Refer to DTC B27A2: Open in Front Passenger Side Electrical Antenna Circuit
B27A5 Open in Front Floor Electrical Key Oscillator Circuit 1. Indoor electrical key oscillator (for front floor)
2. Certification ECU (smart key ECU assembly)
3. Wire harness or connector
Refer to DTC B27A5: Open in Front Floor Electrical Key Oscillator Circuit
B27A6 Open in Rear Floor Electrical Key Oscillator Circuit 1. Indoor electrical key oscillator (for center floor)
2. Certification ECU (smart key ECU assembly)
3. Wire harness or connector
Refer to DTC B27A6: Open in Rear Floor Electrical Key Oscillator Circuit
B27A7 Open in Inside Luggage Compartment Electrical Key Oscillator Circuit 1. Indoor electrical key oscillator (for rear floor)
2. Certification ECU (smart key ECU assembly)
3. Wire harness or connector
Refer to DTC B27A7: Open in Inside Luggage Compartment Electrical Key Oscillator Circuit
B27A8
*
Open in Outside Luggage Compartment Electrical Key Antenna Circuit 1. Outside electrical key oscillator (for rear side)
2. Certification ECU (smart key ECU assembly)
3. Wire harness or connector
Refer to DTC B27A8: Open in Outside Luggage Compartment Electrical Key Antenna Circuit

*: w/ Entry System Back Door Open Function

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:

  • β€’ You smell fuel, burning insulation, or see smoke.
  • β€’ Brakes feel soft, pull hard to one side, or make grinding noises.
  • β€’ The engine overheats, stalls repeatedly, or misfires under load.
  • β€’ You are missing required tools, torque specs, or safe lifting equipment.
  • β€’ You are not confident in the next step or safety outcome.

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