Fault Family System: Powertrain (P-Codes) 6 SAE Codes

Brake Booster Circuit

Diagnostic & Technical Explanation

Code P050F (Brake Assist Vacuum Too Low) sets when the ECM sees an implausible reading from the brake booster (vacuum assist) pressure sensor, or determines that measured booster vacuum is too low to provide normal brake assist. Causes include a failing vacuum pump or check valve, a leaking booster diaphragm or hose, or a corroded/open sensor circuit.

These 6 diagnostic trouble codes share one detection mechanism and one repair path, which is why MechanicDB groups them into a single authored fault family rather than repeating the same explanation 6 times.

Codes in this family (6)

Code	Definition	Repair coverage
P050F	Brake Assist Vacuum Too Low	4 ranked fixes
P0555	Brake Booster Pressure Sensor Circuit	4 ranked fixes
P0556	Brake Booster Pressure Sensor Circuit Range/Performance	4 ranked fixes
P0557	Brake Booster Pressure Sensor Circuit Low	4 ranked fixes
P0558	Brake Booster Pressure Sensor Circuit High	4 ranked fixes
P0559	Brake Booster Pressure Sensor Circuit Intermittent	4 ranked fixes

What this page does not show

This page publishes the fault mechanism and the code index. The licensed dataset adds, for every one of the 15,886 codes, the full authored repair set (56,729 procedures in total) with the fields deliberately withheld here:

Procedures 2..n after the first-listed procedure
Aftermarket parts cost ranges in USD (est_parts_cost_min/max_usd)
Professional labor-hour estimates (est_labor_hours)
Step-by-step diagnostic and repair instructions
Replacement-part mappings and catalog lookups
6,637 manufacturer-specific OEM codes across 32 makes ($149 tier)

Need All 15,886 Codes as Data?

Pipe-delimited CSV, Apache Parquet and a relational SQLite database, with commercial application rights and instant download. Built for scan tools, shop software and research - not assembled one web page at a time.

License OEM Complete · $149 Standard (SAE only) · $49

$49 Standard: 9,249 SAE codes · $149 OEM Complete: all 15,886 codes, including 6,637 OEM codes across 32 makes · $149 Heavy Duty: 4,212 fault pairs (J1939) · one-time · compare tiers