DTC C1252: Wheel Speed Sensor Signal Of One Of The Wheels

DTC detecting condition: 

• Defective ABS wheel speed sensor signal (noise, irregular signal, etc.)
• Defective magnetic encoder
• When a wheel is turned freely for a long time

Trouble symptom: 

• ABS does not operate.
• VDC does not operate.
• EBD may not operate.
• AVH does not function.
• EyeSight does not operate.

Failure detection pattern: 

• "Primary" (high-priority diagnosis)

Warning light/indicator light: 

The combination of DTC and warning light display may differ from the list depending on vehicle conditions and driving conditions at the time of failure detection.

• ABS warning light◦
• VDC warning light & VDC operation indicator light◦
• Electronic parking brake warning light (red)◦
• Brake warning light (EBD warning light) (red)◦

1. WHETHER A WHEEL TURNED FREELY OR NOT  .

   Check if the wheels have been turned freely for one minute or more, such as when the vehicle is jacked-up, under full-lock cornering or when the wheels are not in contact with road surface.

   Did the wheels turn freely?

   Yes:  VDC System is normal. Using the Subaru Select Monitor, perform the clear memory of [Brake Control]. Ref. to COMMON (DIAGNOSTICS)>CLEAR MEMORY .

   NOTE: This diagnostic trouble code may sometimes occur if the wheels turn freely for a long time, for example when the vehicle is towed or jacked-up, or when steering wheel is continuously turned all the way.

   No:  GO TO  2.

2. CHECK TIRE SPECIFICATIONS  .

   Turn the ignition switch to OFF.

   Are the tire specifications correct?

   Yes:  GO TO  3.

   No:  Replace the tire.

3. CHECK WEAR OF TIRE  .

   Is the tire worn excessively?

   Yes:  Replace the tire.

   No:  GO TO  4.

4. CHECK TIRE INFLATION PRESSURE  .

   Is the tire pressure correct?

   Yes:  GO TO  5.

   No:  Adjust the tire pressure.

5. CHECK INSTALLATION OF ABS WHEEL SPEED SENSOR  .

   Are the ABS wheel speed sensor installation bolts tightened to 7.5 N.m (0.76 kgf-m, 5.5 ft-lb)?

   (Four wheels)

   Yes:  GO TO  6.

   No:  Tighten the ABS wheel speed sensor installation bolts.

6. CHECK ABS WHEEL SPEED SENSOR SIGNAL  .

   Check the ABS wheel speed sensor. Ref. to VEHICLE DYNAMICS CONTROL (VDC)>FRONT ABS WHEEL SPEED SENSOR>INSPECTION . Ref. to VEHICLE DYNAMICS CONTROL (VDC)>REAR ABS WHEEL SPEED SENSOR>INSPECTION .

   Is the check result OK?

   Yes:  GO TO  8.

   No:  GO TO  7.

7. CHECK ABS WHEEL SPEED SENSOR OR MAGNETIC ENCODER  .

   Are there foreign matters adhered to the tip of ABS wheel speed sensor or magnetic encoder? Or is there any breakage or damage? (Four wheels)

   Yes:  Remove dirt thoroughly. Also replace the ABS wheel speed sensor or magnetic encoder as a unit with hub unit bearing if it is broken or damaged.

   No:  GO TO  8.

8. CHECK VDCCM & H/U  .
   1. Connect all connectors.
   2. Using the Subaru Select Monitor, perform the clear memory of [Brake Control]. Ref. to COMMON (DIAGNOSTICS)>CLEAR MEMORY .
   3. Execute the inspection mode. Ref. to BRAKE CONTROL (DIAGNOSTICS)>INSPECTION MODE .
   4. Read the DTC of [Brake Control] using the Subaru Select Monitor. Ref. to BRAKE CONTROL (DIAGNOSTICS)>DIAGNOSTIC TROUBLE CODE (DTC) .

   Is the same DTC displayed?

   Yes:  Replace the VDCCM & H/U. Ref. to VEHICLE DYNAMICS CONTROL (VDC)>VDC CONTROL MODULE AND HYDRAULIC CONTROL UNIT (VDCCM & H/U) .

   No:  GO TO  9.

9. CHECK DETECTION OF OTHER DTCS FOR VDC  .

   Read the DTC of [Brake Control] using the Subaru Select Monitor. Ref. to BRAKE CONTROL (DIAGNOSTICS)>DIAGNOSTIC TROUBLE CODE (DTC) .

   Is any other DTC displayed?

   Yes:  Perform the diagnosis according to the DTC. Ref. to BRAKE CONTROL (DIAGNOSTICS)>DIAGNOSTIC TROUBLE CODE (DTC)>LIST .

   No:  Currently, it is normal. There may have been a temporary poor contact in the harness and connector or a temporary noise interference.