Chassis, generic

C063B Brake Pressure Sensor H Circuit Low

Check engine lightUsually off
EmissionsNot relevant
Drive cycleNot required
Limp modePossible

C063B says sensor H reads below its valid floor. Unlike C063C the problem is electrical, not a believable but wrong pressure. A Bosch workshop article on a Teves MK60 unit describes the integrated sensor: fed with 5 V, it stays below 1 V with the brakes off and climbs as pedal pressure builds, so the fault limit has to sit well under that rest level. GM's 2019 EBCM flags its circuit pressure sensor as shorted low when the main channel falls under 4.61 % of supply, or the reference channel under 4.85 %, for 100 ms. Where H sits is not published; in Toyota's eight-sensor design the candidates would be a wheel cylinder, the booster chamber or the pump output. Likely: signal shorted to ground, collapsed 5 V reference or a dead sensor.

Likely causes

Signal conductor shorted to ground
5 V reference collapsed by a short in another sensor on the same feed
Sensor H without output due to an internal defect

Symptoms

  • ABS and ESC lamps on
  • Brake assist and stability control not available

Repair estimate

DifficultyHardWorkshop job
Parts and labour€60–1,800
Time0.5–4 h

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

Parts involved

brake pressure sensor hsensor wiring

Related codes

C0639C063AC063CC0637C063F

References: patents.google.com, techtips.ie, gsi.ext.gm.com.