C004B — Brake Fluid Level Sensor/Switch Circuit/Open

What Does C004B Mean?

C004B is a diagnostic trouble code indicating: Brake Fluid Level Sensor/Switch Circuit/Open. This code relates to the chassis system. The vehicle's computer detected a condition outside normal operating parameters and stored this code.

Symptoms of C004B

⚠️ Check Engine Light (MIL) illuminated
⚠️ Erratic Brake Fluid Level Sensor/Switch readings
⚠️ Related system operating intermittently
⚠️ ABS or stability control warning light

Common Causes

🔍 Wiring issue in Brake Fluid Level Sensor/Switch circuit (damaged, chafed, or corroded)
🔍 Faulty Brake Fluid Level Sensor/Switch connector or terminal
🔍 Failed Brake Fluid Level Sensor/Switch
🔍 ECM/PCM connection issue

Frequently Asked Questions

What does C004B mean?

C004B indicates: Brake Fluid Level Sensor/Switch Circuit/Open. The vehicle's computer has detected that the Brake Fluid Level Sensor/Switch is not operating within its expected parameters and stored this diagnostic trouble code.

Can I drive with code C004B?

Only short distances if absolutely necessary. C004B affects a critical system and should be diagnosed within a few days to avoid further damage.

How much does it cost to fix C004B?

Repair costs for C004B typically range from $100 to $400, depending on the root cause. Simple wiring or connector repairs are on the lower end, while component replacement costs more. A proper diagnosis ($80–$150 at most shops) will identify the exact cause before committing to expensive parts.

What To Do Next

Possible Fixes

🔧 Inspect and repair Brake Fluid Level Sensor/Switch wiring and connectors
🔧 Replace faulty Brake Fluid Level Sensor/Switch

1
Find your vehicle above
Click your make and model for real owner reports and common causes specific to your vehicle.
2
Check for recalls
Go to nhtsa.gov/recalls and enter your VIN. Free repairs if covered.
3
Get a professional diagnosis
A code alone doesn't identify the exact failed part. A diagnostic ($50–$150) pinpoints the root cause.

C004B: Brake Fluid Level Sensor/Switch Circuit/Open