OBD Guide

C1238

ABS Hydraulic Pressure Differential Switch Input Circuit Failure

C1238 is an OBD-II diagnostic trouble code meaning: ABS Hydraulic Pressure Differential Switch Input Circuit Failure. Common causes: malfunction of the differential pressure sensor, open or shorted wiring harness. Estimated repair cost: $56–167.

Severity
⚠️ Medium
Can you drive?
Do not drive — repair immediately
Approx. repair cost
$56–167 (est.)

Symptoms

  • ABS light is on
  • ABS does not activate when braking
  • Uneven braking on slippery surfaces

Causes

  • Malfunction of the differential pressure sensor
  • Open or shorted wiring harness
  • Problems with sensor connectors
  • ABS control unit malfunction

How to Fix

  1. Diagnosing the Sensor Circuit Using a Multimeter
  2. Checking the resistance and voltage on the sensor
  3. Inspect the wiring harness for damage
  4. Replacing the sensor or repairing the circuit if necessary
  5. Resetting errors and testing the system

Related codes

FAQ

What does the C1238 code mean?

C1238 is an OBD-II diagnostic trouble code that indicates: ABS Hydraulic Pressure Differential Switch Input Circuit Failure

What causes a C1238 error code?

The most common causes of C1238 include: Malfunction of the differential pressure sensor; Open or shorted wiring harness; Problems with sensor connectors; ABS control unit malfunction.

How do I fix a C1238 diagnostic trouble code?

To fix C1238: Diagnosing the Sensor Circuit Using a Multimeter. Checking the resistance and voltage on the sensor. Inspect the wiring harness for damage. For a complete diagnosis, use an OBD-II scanner.

Is it safe to drive with C1238?

Do not drive — repair immediately

How much does it cost to fix C1238?

The estimated repair cost for C1238 is $56–167. Actual cost depends on your vehicle, location, and labor rates.

See also: Russian version · NationStat