C1238 Code: ABS Hydraulic Pressure Differential Switch Input Circuit Failure
🟠 Moderate severity · drivable
Drivable — standard brakes still work — but ABS may be disabled, so drive cautiously and fix it soon.
What C1238 means
The ABS hydraulic pressure differential switch input circuit has a fault. This switch detects a brake-pressure difference between the two brake circuits.
Symptoms
- ABS warning light on
- ABS disabled (no pulsing during hard stops)
- Possible brake warning lamp
Common causes
- most common: Faulty pressure differential switch
- common: Damaged wiring or connector
- less common: Faulty ABS hydraulic unit
How to fix it
| Fix | DIY? | Typical cost |
|---|---|---|
| Repair damaged switch wiring | Mechanic | $50–150 |
| Replace the ABS hydraulic unit | Mechanic | $400–1200 |
Frequently asked questions
Can I drive with a C1238 code?
Yes, regular brakes still work, but ABS may be disabled. Drive cautiously.
What is the most common cause of C1238?
A faulty pressure differential switch.
How much does it cost to fix a C1238?
$50–$150 for wiring, or $400–$1,200 for a hydraulic unit.
Related codes
C1239
C1239 Code: ABS Hydraulic Pressure Differential Switch Input Open Circuit
C1100C1100 Code: ABS Pump Switch Circuit Failure
C1095C1095 Code: ABS Hydraulic Pump Motor Circuit Failure
Updated 2026-08. This page is informational and not a substitute for professional diagnosis.