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.
DTC B2B09 Driver's Door Power Window Control Module EEPROM
DTC detecting condition:
When one of the following data cannot be read from the non-volatile memory as the CPU is reset.
- Window position
- Sliding learn value
- Initialization completed state
- Full open stop position
Trouble symptom:
- When the power window main switch is operated, driver's side window does not work.
- When the power window main switch is operated, driver's side window rolls down only in manual down operation, or inches up. (Inch up: Operating the switch rolls up the window about 10 mm only)CAUTION: Before performing diagnosis, refer to "CAUTION" in "General Description". Ref. to POWER WINDOW (DIAGNOSTICS)>General Description>CAUTION .
- INITIALIZATION BY POWER WINDOW SWITCH (DRIVER'S SIDE)
.
- Perform initialization using the power window switch. Ref. to POWER WINDOW (DIAGNOSTICS)>Work Support>NOTE .
- Read the DTC of [Power Window (Driver)] using the Subaru Select Monitor. Ref. to POWER WINDOW (DIAGNOSTICS)>DIAGNOSTIC TROUBLE CODE (DTC) .
Is DTC B2B09 displayed? (Current malfunction)
Yes: Go to 2 .
No: Even if DTC is displayed, 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. - SYSTEM INITIALIZATION
.
- Using the Subaru Select Monitor, perform [System Initialization] of [Power Window (Driver)]. Ref. to POWER WINDOW (DIAGNOSTICS)>Work Support>OPERATION>SYSTEM INITIALIZATION .NOTE: Record the DTCs and FFD because they will be erased when the initialization is performed.
- Read the DTC of [Power Window (Driver)] using the Subaru Select Monitor. Ref. to POWER WINDOW (DIAGNOSTICS)>DIAGNOSTIC TROUBLE CODE (DTC) .
Is DTC B2B09 displayed? (Current malfunction)
Yes: Replace the front regulator and motor assembly (driver's side). Ref. to GLASS/WINDOWS/MIRRORS>FRONT REGULATOR AND MOTOR ASSEMBLY .
No: Even if DTC is displayed, 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. - Using the Subaru Select Monitor, perform [System Initialization] of [Power Window (Driver)]. Ref. to POWER WINDOW (DIAGNOSTICS)>Work Support>OPERATION>SYSTEM INITIALIZATION .
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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.