Fault Family System: Network (U-Codes) 9 SAE Codes

HS CAN Bus Fault

Diagnostic & Technical Explanation

Code U0001 sets when the powertrain/chassis high-speed CAN backbone -- the 500 kbps twisted, shielded pair linking the PCM, TCM, ABS and other safety-critical modules -- stops passing valid frames or reports excessive bus errors. The bus relies on exactly two 120-ohm terminating resistors, one at each end, so it should read close to 60 ohms across CAN-H and CAN-L with the ignition off and all modules asleep. Most failures trace to a chafed harness section near the engine bay or firewall grommet, a corroded splice, or a terminating resistor that has opened inside a damaged module.

These 9 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 9 times.

Codes in this family (9)

Code	Definition	Repair coverage
U0001	High Speed CAN Communication Bus	4 ranked fixes
U0002	High Speed CAN Communication Bus Performance	4 ranked fixes
U0003	High Speed CAN Communication Bus (+) Open	4 ranked fixes
U0004	High Speed CAN Communication Bus (+) Low	4 ranked fixes
U0005	High Speed CAN Communication Bus (+) High	4 ranked fixes
U0006	High Speed CAN Communication Bus (-) Open	4 ranked fixes
U0007	High Speed CAN Communication Bus (-) Low	4 ranked fixes
U0008	High Speed CAN Communication Bus (-) High	4 ranked fixes
U0009	High Speed CAN Communication Bus (-) shorted to Bus (+)	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)

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