🚨 Diagnostic Profile
- Vehicle/Equipment Make: GENERIC
- Technical Description: Brake Booster Temperature Sensor B Circuit/Open
This code is set by the Electronic Brake Control Module (EBCM) when it detects an open circuit, short, or out-of-range signal from the secondary (B) temperature sensor associated with the brake booster vacuum pump assembly. Many modern vehicles use an electric vacuum pump to assist the brake booster, especially on vehicles with stop/start or hybrid-type powertrains where a traditional engine-driven vacuum source is insufficient or intermittent. The temperature sensor monitors the pump motor’s thermal condition to prevent overheating. When Sensor B’s circuit is open or reads erratically, the module cannot verify motor temperature, so it restricts booster pump operation and may disable traction control or stability control assist functions as a safety precaution until the fault is cleared. This is strictly a chassis-level brake system code and is unrelated to engine control or exhaust emissions circuits.
🚨 Repair Difficulty Tier
- Difficulty Rating: Intermediate
This repair requires a scan tool capable of reading ABS/EBCM-specific chassis codes and live data streams, along with a digital multimeter to test circuit continuity and resistance values. While the booster pump assembly itself can be accessed with basic hand tools, correctly diagnosing a wiring fault versus a failed sensor requires some electrical diagnostic experience.
🛠️ Resolution Steps
- Step 1: Preliminary Inspection
Locate the brake booster vacuum pump assembly (typically mounted near the master cylinder or under the vehicle near the brake lines) and visually inspect the wiring harness and connector for corrosion, chafing, or disconnection at the temperature sensor pigtail. Check for any signs of moisture intrusion or melted insulation near the pump motor housing. - Step 2: Diagnostic Verification
Using a scan tool, access the EBCM/ABS module live data and monitor Sensor B temperature readings for erratic behavior, a fixed default value, or an out-of-range fault flag. With the key off and harness disconnected, use a digital multimeter to measure resistance across the sensor B terminals and compare against manufacturer specifications; also check for continuity across the full length of wiring back to the EBCM connector to rule out a chafed or broken wire. - Step 3: Resolution & Reset Process
If the sensor itself is open or out of specification, replace the temperature sensor component or, if integrated, the full booster pump motor assembly. If the wiring harness is damaged, repair or replace the affected harness section with proper weatherproof connectors. After repair, clear the stored code using the scan tool and perform a system self-test or bleed cycle to confirm the EBCM recognizes normal sensor operation and that brake assist functions and stability/traction control indicators return to normal status.
📦 Parts, Labor, and Budget Estimates
- Required Components/Software: Brake booster vacuum pump temperature sensor (or full pump assembly), wiring harness repair kit/connectors, OBD-II/chassis-capable scan tool
- Average Component Price: $60 – $280 USD
- Estimated Labor Hours: 0.8 – 1.5 hours
- Total Estimated Budget: $140 – $420 USD