C1421 2018 Toyota RAV4 Code - Open or Short in Master Cylinder Pressure Sensor

Code C1421 indicates an open or short circuit in the master cylinder pressure sensor circuit, which monitors brake pressure for proper ABS and traction control operation.

Symptoms may include illuminated ABS, traction control, or brake warning lights, reduced braking efficiency, or loss of traction control functionality.

Common causes include damaged wiring or connectors in the pressure sensor circuit, a faulty master cylinder pressure sensor, or issues with the ABS control module.

While you may still be able to drive, it’s not recommended as the ABS and traction control systems may not function properly, increasing the risk of an accident in emergency braking situations.

Start by inspecting the wiring and connectors for damage or corrosion. Use a multimeter to check for continuity and voltage in the master cylinder pressure sensor circuit. If these are fine, test or replace the sensor.

Repair costs can vary. Replacing a master cylinder pressure sensor typically costs $200–$400, while fixing wiring or connector issues may range from $50–$200 depending on labor and parts.

After repairing the issue, use an OBDII scanner to clear the code. If the problem persists, the code will return, indicating further diagnosis is required.

Yes, a faulty sensor can lead to additional ABS or traction control-related codes, as it directly impacts these systems’ functionality.

You’ll need an OBDII scanner, a multimeter for electrical testing, and basic hand tools for inspecting or replacing the sensor and wiring.

While low brake fluid can trigger other brake-related warnings, it is unlikely to cause the C1421 code, which specifically relates to the master cylinder pressure sensor circuit.