C1940 Code: Meaning, Symptoms, Causes & Fix

Overview

Code C1940 indicates a fault in Brake Pressure Switch Mechanical Failure, typically within ABS/chassis dynamics and brake control.

Symptoms

chassis warning indicator
reduced stability control performance
longer braking intervention

Common causes

Control module logic or calibration issue affecting brake pressure switch mechanical failure
Component failure in the monitored system
Connector pin damage/corrosion or harness stress near related components

How to diagnose C1940

Confirm C1940 and capture freeze-frame data with a professional scan tool.
Inspect wiring, connectors, and grounds related to brake pressure switch mechanical failure for obvious defects.
Use freeze-frame and live data to isolate whether the issue is electrical, mechanical, or control logic.
Check for related DTCs to identify the root-cause chain before replacing parts.
After repair, clear codes and confirm readiness monitors complete without recurrence.

Severity of code C1940

Low: This code is low to moderate severity in most cases, but diagnosis is still recommended to avoid recurring warnings.

Can you drive with C1940?

The vehicle is often drivable with C1940, but plan a repair window to prevent repeat faults.

If the warning lamp is flashing or drivability/safety is affected, avoid driving and diagnose immediately.

How to fix it (step-by-step)

Repair obvious wiring/connector faults first to prevent repeat parts replacement.
Address the root fault mode (generic) in the brake pressure switch mechanical failure circuit/system.
Apply the required relearn/adaptation procedure if specified by service information.
Road-test and verify C1940 remains cleared under the conditions that originally set the code.

Fix options

Test component operation and replace if faulty.
Clear code and confirm through drive cycle.
Clear DTCs and verify with live data and completed drive cycle.

Typical repair cost

$120-$500

Common mistakes when diagnosing C1940

Replacing parts without verifying voltage, ground, and signal integrity first.
Ignoring related stored/pending codes that indicate upstream faults.
Skipping post-repair verification drive cycle and readiness checks.

C1940 in common vehicles

C1940 appears across makes such as Nissan, Hyundai, Kia, Volkswagen. Failure patterns differ by platform: wiring routes, software calibration, and component supplier revisions can change root cause.

Frequently asked questions

What causes C1940?

C1940 is commonly set by generic faults affecting brake pressure switch mechanical failure.

How much does it cost to fix C1940?

For C1940, repair costs are typically $120-$500 depending on exact root cause, labor rates, and part quality.

Can I clear C1940 without repair?

You can clear C1940 temporarily, but the code usually returns until the underlying fault is corrected.