C0049: Brake Fluid (Subfault)

What it means

This code identifies a fault associated with the brake fluid system. The specific failure depends on the diagnostic subtype.

At a glance

• Usually lights the ABS or stability-control warning light

How it works

This subfault code concerns the brake fluid system, which may include fluid level sensing and its signal to the brake control module. The subtype is needed to tell whether the issue is low fluid, a sensor or wiring fault, or a module-related fault.

Common causes

Most likely first.

1. Brake fluid level too low
2. Brake fluid level sensor failure
3. Damaged sensor wiring or connector
4. Brake control module fault

Symptoms

• Brake or ABS warning light
• Brake fluid warning may appear

How to diagnose it

1. Read the subtype and freeze-frame data to determine which brake-fluid condition the control module detected.
2. With the vehicle on level ground, check the reservoir level and look for visible signs of a fluid leak around the reservoir, lines, and wheels.
3. Inspect the fluid level sensor, connector, and wiring for damage, corrosion, or a loose connection.
4. Check the sensor circuit for opens or shorts and verify its signal at the module using the wiring diagram and manufacturer's specification.
5. If fluid level and wiring are correct, test the sensor and module input according to the manufacturer's procedure.

Common fixes

• Repair any brake fluid leak and correct the fluid level using the specified fluid.
• Reconnect or repair damaged fluid-level sensor wiring or connector terminals.
• Replace a faulty brake fluid level sensor or switch.
• Repair the brake control module only if its input is confirmed faulty.

Can I keep driving?

Check the fluid level promptly; low fluid can indicate a leak and may compromise braking. Do not drive if the level is below minimum, a leak is visible, or braking feels abnormal; have the vehicle assessed.