Chassis, generic

C0542 Brake Pressure Sensor B Circuit Low

Check engine lightOn
EmissionsNot relevant
Drive cycleNot required
Limp modePossible

Brake pressure sensor B pulls its signal below the lowest voltage the receiving module treats as valid. Two makers name the code in public bulletins. Bentley lists C054200 in the ESC unit J104 of the Continental GT/GTC and Flying Spur alongside C054100, with adaptive cruise switched off and the J104 replaced. Stellantis lists C0542 as Brake Pressure Sensor 2 Circuit Low among powertrain-module faults of the 2019 Jeep Cherokee with 3.2-litre V6 and engine stop-start; there a PCM software update was the remedy, with a check-engine lamp as the complaint. As a reference for the electrical limit, a Saab 9-5 brake unit treats anything under 0.25 V lasting 0.1 s as a sensor fault. Signal shorts to ground, a missing 5-V feed or a failed sensor are the usual causes.

Likely causes

Signal line shorted to ground
Sensor or the ESC unit with integrated sensor defective
Engine control software misjudging the signal (Jeep Cherokee 2019)
5-V sensor supply dragged down

Symptoms

  • Check-engine or ESC warning lamp on
  • Adaptive cruise control or stop-start unavailable

Repair estimate

DifficultyMediumWorkshop job
Parts and labour€60–2,500
Time0.3–3 h

Typical range across vehicles; the real cost depends on what the testing finds.

Parts involved

brake pressure sensor bsensor wiring

Related codes

C0541C0543C0544C053E

References: static.nhtsa.gov, static.nhtsa.gov, static.nhtsa.gov, saabwisonline.com.