Fault Family System: Powertrain (P-Codes) 3 SAE Codes

Regeneration Control Switch

Diagnostic & Technical Explanation

Code P25BA (Regeneration Control Switch Circuit/Open) sets when the ECM sees an open, shorted, or out-of-range signal from the driver's regeneration control switch, used on diesel work trucks to request a parked regeneration or to inhibit regeneration during indoor or flammable-cargo operation. Causes are worn switch contacts, a corroded connector in the dash harness, or chafed wiring to the ECM.

These 3 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 3 times.

Codes in this family (3)

Code	Definition	Repair coverage
P25BA	Regeneration Control Switch Circuit/Open	3 ranked fixes
P25BB	Regeneration Control Switch Circuit Low	3 ranked fixes
P25BC	Regeneration Control Switch 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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