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 MANUALSSUBARU2022IMPREZA BASE, 4D SEDAN, AUTOMATIC CVT TRANSREPAIR AND DIAGNOSISENGINE PERFORMANCETESTING & DIAGNOSISAUTO START STOP (DIAGNOSTICS)DIAGNOSTIC PROCEDURE WITH DIAGNOSTIC TROUBLE CODE (DTC)DTC P1A16: DC/DC CONVERTER 1 BOOST COMMAND SIGNAL HIGHNOTES

2022 Subaru Impreza Base, 4D Sedan, Automatic CVT Trans

DTC P1A16: Dc/Dc Converter 1 Boost Command Signal High: Notes

2022 Subaru Impreza Base, 4D Sedan, Automatic CVT TransSECTION Notes

1. -

DTC detecting condition:

Detected when two consecutive driving cycles with fault occur.

Trouble symptom:

Auto Start Stop does not operate.

Wiring diagram:

Auto Start Stop Ref. to WIRING SYSTEM (CROSSTREK MODEL (EXCEPT FOR HEV))>AUTO START STOP .

Courtesy of SUBARU OF AMERICA, INC.

CAUTION:

Use the check board when measuring the ECM terminal voltage and resistance.
After servicing or replacing faulty parts, perform the last step of the basic diagnostic procedure. Ref. to AUTO START STOP (DIAGNOSTICS)>BASIC DIAGNOSTIC PROCEDURE .

CHECK DATA MONITOR .
1. Turn the ignition switch to ON.
2. Read the data of [DC/DC Converter 1 Boost Signal Reception] using Subaru Select Monitor. Ref. to AUTO START STOP (DIAGNOSTICS)>DATA MONITOR .
Is [Reception] displayed in [DC/DC Converter 1 Boost Signal Reception]?

Yes: Go to 2.

No: The circuit has returned to a normal condition at this time. Reproduce the failure, and then perform the diagnosis again.

NOTE:
In this case, temporary poor contact of connector, temporary open or short circuit of harness may be the cause.
CHECK DC/DC CONVERTER 1 BOOST COMMAND SIGNAL .
1. Turn the ignition switch to OFF.
2. Disconnect the DC/DC converter 1 connector.
3. Turn the ignition switch to ON.
4. Measure the voltage between DC/DC converter 1 connector and chassis ground.
  Connector and terminal
  
  (B562) No. 11 (+) - Chassis ground (-):
Is the voltage 5 V or more?

Yes: Go to 3.

No: Repair the poor contact of DC/DC converter 1 connector. Replace the DC/DC converter 1 if defective. Ref. to STARTING/CHARGING SYSTEMS (H4DO (EXCEPT FOR HEV))>AUTO START STOP DC/DC CONVERTER .
CHECK HARNESS BETWEEN ECM AND DC/DC CONVERTER 1 .
1. Turn the ignition switch to OFF.
2. Disconnect the ECM connector.
3. Turn the ignition switch to ON.
4. Measure the voltage between ECM connector and chassis ground.
  Connector and terminal
  
  (B134) No. 7 (+) - Chassis ground (-):
Is the voltage 5 V or more?

Yes: Repair the short circuit to power supply in harness between ECM and DC/DC converter 1.

No: Check for poor contact of ECM connector. Replace the ECM if no fault is found. Ref. to FUEL INJECTION (FUEL SYSTEMS) (H4DO (EXCEPT FOR HEV))>ENGINE CONTROL MODULE (ECM) .

RENDER: 1.0x

NO RELATED

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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.