Chassis, generic

C0046 Brake Pressure Sensor A/B

Check engine lightUsually off
EmissionsNot relevant
Drive cycleNot required
Limp modePossible

A correlation code for the pair of brake pressure sensors A and B, set when their readings do not agree within the expected tolerance. Where C0044 and C0045 flag a single-sensor electrical fault, this code is a plausibility fault: at the same instant both sensors should report consistent pressure (allowing for their known relationship), and a persistent mismatch indicates one sensor has drifted, a hydraulic fault separates the circuits, or a signal is corrupted. The stability and brake modules rely on agreement to trust the pressure reading for stability, brake assist and brake-by-wire control. A fault disables those functions and sets the ABS or brake warning lamp while base braking remains. NHTSA lists C0046 in the J2012 table of its EPS report. No manufacturer documents it publicly.

Likely causes

One pressure sensor drifted or biased
Hydraulic fault separating the circuits
Signal corruption or wiring fault

Symptoms

  • ABS or brake warning lamp on
  • Stability and assist functions disabled
  • Changed brake assist behaviour

Repair estimate

DifficultyShop_onlyWorkshop job
Parts and labour€400–2,200
Time1.5–4 h

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

Parts involved

brake pressure sensors

Related codes

C0044C0045C0024

References: rosap.ntl.bts.gov, rosap.ntl.bts.gov, en.wikipedia.org.