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Home >> Audi >> 2015 >> A4 Prestige >> Repair and Diagnosis >> External Pages >> Different car >> Section 420 (Electronically Controlled Brake System (Diagnostic Codes & Symptom Tests)) >> Electronically Controlled Brake System >> DTC C1246/46: Master Cylinder Pressure Sensor Malfunction; DTC C1281/81: Master Cylinder Pressure Sensor Output Malfunction (Test Mode DTC); DTC C1364/61: Wheel Cylinder Pressure Sensor Malfunction [08/2013 - ] >> Description

DTC C1246/46: Master Cylinder Pressure Sensor Malfunction; DTC C1281/81: Master Cylinder Pressure Sensor Output Malfunction (Test Mode DTC); DTC C1364/61: Wheel Cylinder Pressure Sensor Malfunction [08/2013 - ]: Description

WARNING: This page is about a different car, the 2014 Lexus ES 300h. However, it is still accessible from the selected car via links, so may be relevant.

The regulator pressure sensor and wheel cylinder pressure sensor are built into the brake actuator. They measure their respective pressures and send signals to the skid control ECU (brake booster with master cylinder assembly).

DTC C1281/81 will be cleared when the regulator pressure sensor sends a regulator pressure signal or when Test Mode ends. DTC C1281/81 is output only in Test Mode.

DTC No. INF Code DTC Detection Condition Trouble Area
C1246/46 201 Sensor supply voltage (VCM1) is 4.75 V or less, or 5.25 V or more for 0.05 seconds. Brake booster with master cylinder assembly
202 Regulator pressure sensor output voltage (Preg) is less than 8%, or 90.3% or more (less than 0.4 V, or 4.52 V or more) of sensor supply voltage (VCM1) for 0.05 seconds or more.
203 When not under braking, the regulator pressure sensor output voltage is 0.2 V or less or 0.88 V or more for 3 seconds or more.
204 Either of the following is detected:
  1. The regulator pressure sensor output voltage does not correspond with brake pedal stroke sensor assembly and the readings remain out of specification for 0.5 to 5 seconds or more continuously.

    (The brake pedal stroke sensor assembly may be malfunctioning.)

  2. The regulator pressure sensor output voltage does not correspond with wheel cylinder pressure sensor and the outputs remain out of specification for 0.5 to 5 seconds or more continuously.

    (May be output with INF code 424.)

  • Brake pedal stroke sensor assembly
  • Brake booster with master cylinder assembly
207 Fluctuation of regulator pressure sensor output is out of specification (the difference between the present value and last value is 15 MPa (153.0 kgf/cm2 , 2176 psi) or more) for 0.1 seconds or more. Brake booster with master cylinder assembly
C1364/61 421 Sensor supply voltage 1 (VCM1) is 4.75 V or less, or 5.25 V or more for 0.05 seconds or more. Brake booster with master cylinder assembly
422 Wheel cylinder pressure sensor output voltage (Pfront) is less than 8%, or 90.3% or more (less than 0.4 V, or 4.52 V or more) of sensor supply voltage (VCM1) for 0.05 seconds or more.
423 When not under braking, the wheel cylinder pressure sensor output voltage is 0.2 V or less or 0.88 V or more for 0.1 to 3 seconds or more.
424 The wheel cylinder pressure sensor output voltage does not correspond with regulator pressure sensor and the outputs remain out of specification for 0.5 to 5 seconds or more continuously.
(May be output with INF code 204.)
426 Fluctuation of wheel cylinder pressure sensor output is out of specification (the difference between the present value and last value is 15 MPa (153.0 kgf/cm2 , 2176 psi) or more) for 0.1 seconds or more.
C1281/81 - Detected only during Test Mode.
  • Stop light switch assembly
  • Regulator pressure sensor (Brake booster with master cylinder assembly)