C0547: Vacuum Sensor Supply Voltage Circuit/Open

What it means

Open circuit on the vacuum sensor supply voltage line. Vacuum sensors are used in vacuum-assisted brake boosters to monitor manifold or booster vacuum.

How it works

The vacuum sensor supply circuit provides the power the sensor needs to report vacuum used by a vacuum-assisted brake system. The control module sets this code when it detects an open in that supply circuit, so the sensor may not operate and brake assist may be affected.

Common causes

Most likely first.

1. Supply wiring open
2. Pin pushed back out of connector body
3. Cracked solder joint inside the module or sensor

Symptoms

• Brake or stability-control warning light on
• Brake assist may be affected

How to diagnose it

1. Scan the brake or stability control module for related codes and check live vacuum sensor data, if available, to see whether the reading is missing.
2. Inspect the vacuum sensor connector for a backed-out pin, loose fit, corrosion, or water intrusion.
3. Follow the sensor supply wire and check for a break, damaged insulation, or poor connection at a splice.
4. Use the vehicle wiring information to test continuity in the supply circuit between the module and sensor.
5. If the wiring and terminals pass, test the sensor and module supply connections according to the manufacturer's procedure.

Common fixes

• Reconnect a pushed-back supply terminal at the sensor.
• Repair a broken or damaged supply wire.
• Clean or repair corroded connector terminals or a poor splice.
• Repair a confirmed internal sensor or module connection fault.

Can I keep driving?

Because brake assist may be reduced, the pedal may require more effort and stopping can become harder. If the pedal feels unusually hard or braking is impaired, stop in a safe place and arrange assistance; otherwise drive cautiously and get the fault checked promptly.