Faulty brake booster temperature sensor B; Short to ground in the sensor signal circuit; Damaged or corroded wiring harness or connector at the sensor; Poor electrical connection or high resistance in the ground circuit; Failed brake booster control module or integrated power brake assembly; Overheating brake booster due to a stuck brake caliper or dragging brakes; Aftermarket or incorrect sensor installed previously

DTC codes / C05xx · Brakes, steering and suspension / C0579

C0579Brake Booster Temperature Sensor B Circuit Low

Q: What does code C0579 mean?

Brake Booster Temperature Sensor B Circuit Low. This code means the brake booster temperature sensor on circuit B is reporting a voltage lower than the manufacturer's expected range, which the control module interprets as an excessively hot or shorted sensor signal. The computer has detected a low-voltage condition on that sensor circuit, typically below 0.2 volts, indicating a possible short to ground, faulty sensor, or wiring problem.

This code means the brake booster temperature sensor on circuit B is reporting a voltage lower than the manufacturer's expected range, which the control module interprets as an excessively hot or shorted sensor signal. The computer has detected a low-voltage condition on that sensor circuit, typically below 0.2 volts, indicating a possible short to ground, faulty sensor, or wiring problem.

SystemChassis

Code typeGeneric (all makes)

SeverityMedium

Fix difficultyProfessional

AreaBrakes, steering and suspension

Symptoms you may notice

Illumination of the brake system warning light or ABS light on the dashboard
Often no symptoms besides the warning light, especially in early stages
Reduced or inconsistent brake assist, requiring more pedal effort
A burning smell or visible smoke from the brake booster area in severe cases
Intermittent brake performance or a spongy brake pedal feel
Possible activation of a fail-safe mode limiting vehicle speed

Common causes, most likely first

Faulty brake booster temperature sensor B
Short to ground in the sensor signal circuit
Damaged or corroded wiring harness or connector at the sensor
Poor electrical connection or high resistance in the ground circuit
Failed brake booster control module or integrated power brake assembly
Overheating brake booster due to a stuck brake caliper or dragging brakes
Aftermarket or incorrect sensor installed previously

How to diagnose and fix it

Scan all modules for stored and pending codes, and record freeze-frame data to understand when the fault occurred
Visually inspect the sensor, connector, and wiring for damage, corrosion, or loose pins
Measure sensor resistance and compare to manufacturer specifications; replace if out of range
Check for a short to ground in the signal circuit using a multimeter and wiring diagram
Verify ground integrity and repair any high-resistance grounds
If wiring and sensor are good, test the control module and replace if necessary
Clear codes and perform a road test to confirm the repair

Don't overlook the brake booster itself

A dragging brake caliper or a stuck parking brake can overheat the brake booster and trigger this code, so always check for excessive brake heat.
The sensor is often integrated into the brake booster assembly and may not be serviceable separately, requiring replacement of the entire unit.
A low-voltage code can be set by a poor ground connection rather than a faulty sensor, so ground integrity must be verified before replacing parts.
This code can be intermittent and may only appear after extended driving or heavy braking, so a thorough road test is essential for diagnosis.
Some vehicles use the brake booster temperature sensor to monitor for overheating during regenerative braking, and a fault can disable regenerative braking, affecting fuel economy.

Can I keep driving with C0579?

If the brake pedal feels normal and the warning light is steady, you can drive cautiously to a repair shop, but avoid heavy braking or towing. If the pedal is spongy, brake assist is reduced, or the light is flashing, stop driving and have the vehicle towed to prevent brake failure.

Tools that help

Tools we recommend are in the Auto Veteran shop on Amazon. As an Amazon Associate we earn from qualifying purchases.

Guidance is general and written for all OBD-II vehicles. Exact tests and values vary by model, so confirm the fault before replacing parts.