Fault Family System: Powertrain (P-Codes) 7 SAE Codes

HV Battery Negative Contactor

Diagnostic & Technical Explanation

Code P0AA3 sets when the battery management system commands the HV battery pack's main negative contactor open or closed and its auxiliary feedback contact does not confirm the commanded state, or the bus voltage does not rise/fall as expected within the timing window. The most common physical causes are pitted or welded contact tips, a corroded or unseated coil-driver connector, and a failed coil winding — the negative contactor sees the same current path as the positive contactor but completes the return side of the circuit, so the two are diagnosed with the same procedure but are never assumed to share a single point of failure.

These 7 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 7 times.

Codes in this family (7)

Code	Definition	Repair coverage
P0AA3	Hybrid/EV Battery Negative Contactor Circuit	3 ranked fixes
P0AA4	Hybrid/EV Battery Negative Contactor Circuit Stuck Closed	3 ranked fixes
P0AA5	Hybrid/EV Battery Negative Contactor Circuit Stuck Open	3 ranked fixes
P0ADD	Hybrid/EV Battery Negative Contactor Control Circuit/Open	3 ranked fixes
P0ADE	Hybrid/EV Battery Negative Contactor Control Circuit Range/Performance	3 ranked fixes
P0ADF	Hybrid/EV Battery Negative Contactor Control Circuit Low	3 ranked fixes
P0AE0	Hybrid/EV Battery Negative Contactor Control Circuit High	3 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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