OBD Guide

C1239

ABS Hydraulic Pressure Differential Switch Input Open Circuit

Severity
⚠️ Medium
Can you drive?
Limited driving only, diagnose soon
Approx. repair cost
$56–167 (est.)

Symptoms

  • The ABS indicator on the dashboard is on
  • Disabling the ABS system
  • Incorrect operation of the anti-lock braking system

Causes

  • Broken or damaged sensor wiring harness
  • Oxidation of sensor contacts
  • Differential pressure sensor malfunction
  • Problems with the ABS control unit

How to Fix

  1. Check the integrity of the sensor wiring harness
  2. Clean the sensor contacts from oxidation
  3. Check sensor resistance
  4. If necessary, replace the differential pressure sensor
  5. Check the operation of the ABS control unit

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