Code C0645 indicates that the vehicle's stability or brake control module has detected an open circuit in the left brake pressure sensor circuit. This means there is a physical break in the wiring, a disconnected connector, or an internal failure in the sensor that is preventing the electrical signal from being read by the module.
A broken wire, chafed harness, or disconnected plug is the most common cause of an open circuit condition, disrupting the electrical path.
The sensor itself may have an internal open circuit, meaning it can no longer generate or transmit a pressure signal to the control module.
Corrosion within the sensor connector or a terminal that has pushed back out of the connector can interrupt the electrical circuit.
If the ground path for the sensor circuit is compromised or broken, the control module may interpret the lack of return voltage as an open circuit.
A failure inside the module monitoring the circuit is possible but extremely rare, and should only be considered after all wiring and sensors are verified.
An open circuit means there is a break in the electrical path. Electricity cannot flow from the control module to the sensor or back, similar to a broken wire or a disconnected plug.
It is generally not recommended. The ABS, traction control, and stability control systems will likely be disabled, and advanced safety features like automatic emergency braking may not function properly.
No, replacing the control module rarely fixes an open circuit code. Drivers are frequently and incorrectly told to replace the PCM or ABS module for this code, but the problem is almost always a broken wire, corroded connector, or a failed brake pressure sensor. Do not replace the module without thoroughly testing the wiring and sensor first.
While low system voltage can cause erratic sensor readings, it typically causes voltage-low codes rather than an open circuit code like C0645. The root cause of C0645 is almost always a physical break in the circuit.