Fault Family System: Powertrain (P-Codes) 5 SAE Codes

Exhaust Aftertreatment Power Relay Circuit

Diagnostic & Technical Explanation

Code P05F3 (Exhaust Aftertreatment Power Relay Control Circuit/Open) sets when the ECM detects an open circuit, out-of-range voltage, or a stuck-on/stuck-off condition while driving the power relay that keeps the aftertreatment (SCR/DPF) control module powered after key-off to complete regeneration or dosing shutdown sequences. Causes are a failed relay, a blown fuse, or damaged control/power wiring.

These 5 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 5 times.

Codes in this family (5)

Code	Definition	Repair coverage
P05F3	Exhaust Aftertreatment Power Relay Control Circuit/Open	4 ranked fixes
P05F4	Exhaust Aftertreatment Power Relay Control Circuit Low	4 ranked fixes
P05F5	Exhaust Aftertreatment Power Relay Control Circuit High	4 ranked fixes
P05F6	Exhaust Aftertreatment Power Relay Control Circuit Stuck On	4 ranked fixes
P05F7	Exhaust Aftertreatment Power Relay Control Circuit Stuck Off	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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