Easy one-page printout for the garage or repair shop
This summary uses the existing diagnostic information shown in full below.
This code means that the car's computer is having trouble understanding the signals from the brake pressure sensor. It's like the car is confused about how hard you're pressing the brakes.
The brake pressure sensor measures the force applied to the brakes and sends this information to the car's computer. If the signal is outside the expected range, the computer sets this code.
C0644 is triggered when the brake pressure sensor sends a signal to the Electronic Control Module (ECM) that is outside of the expected range. This could be due to a faulty sensor, wiring issues, or problems with the ECM itself.
• ABS warning light on
• Inconsistent brake performance
• Brake pedal feels different
• Faulty brake pressure sensor
• Damaged or corroded wiring/connectors
• Malfunctioning ECM
ECM: Electronic Control Module
ABS: Anti-lock Braking System
• Check for any other related codes.
• Inspect the brake pressure sensor and its wiring for damage.
• Test the sensor's output to ensure it is within specifications.
• Replace the brake pressure sensor if faulty.
• Repair or replace damaged wiring or connectors.
• Reprogram or replace the ECM if necessary.
• OBD-II scanner
• Multimeter
• Wrench set
$150 - $400
Moderate
• Chevrolet Silverado
• GMC Sierra
• Cadillac Escalade
• Regularly inspect brake system components.
• Ensure connectors and wiring are free of corrosion.
• Perform routine maintenance checks on the braking system.
Sensor Issue
• Do not ignore the ABS warning light.
• Have a professional inspect the vehicle if unsure.
• Avoid driving in hazardous conditions until the issue is resolved.
Check with the vehicle manufacturer for specific warranty coverage related to the brake system.
This code has been more commonly reported in vehicles with high mileage or those that have been exposed to harsh environmental conditions.
Moderate – It is important to address this issue to maintain safe braking performance.
Driving with a malfunctioning brake system can be dangerous and may violate vehicle safety laws.
• Vehicle must be stationary.
• Ignition in the 'ON' position without engine running.
The brake pressure sensor is typically located near the brake master cylinder or integrated within the ABS module.
Q: Can I drive with a C0644 code?
A: It's not recommended to drive with this code, as it may affect braking performance.
Q: How do I reset the ABS light?
A: Fix the underlying issue first, then use an OBD-II scanner to clear the code.
Pro · Four-system diagnostics
A handheld scanner aimed at engine, transmission, ABS, and airbag diagnostic work.
Chassis and ABS faults usually need a scanner that can read brake-system data directly.
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