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

Alt Fuel Disable Circuit

Diagnostic & Technical Explanation

Code P25BE (Alternative Fuel Disable Control Circuit/Open) sets when the ECM detects an open, shorted, or out-of-range condition on the control or signal line that disables the alternative-fuel system and reverts the engine to gasoline, used during high-load conditions or when the gas tank runs empty. Causes are a corroded connector between the ECM and the alternative-fuel control module, a failed disable relay, or damaged inter-module wiring.

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
P25BE	Alternative Fuel Disable Control Circuit/Open	3 ranked fixes
P25BF	Alternative Fuel Disable Control Circuit High	3 ranked fixes
P25C0	Alternative Fuel Disable Control Circuit Low	3 ranked fixes
P25C1	Alternative Fuel Disable Signal Circuit	3 ranked fixes
P25C2	Alternative Fuel Disable Signal Circuit High	3 ranked fixes
P25C3	Alternative Fuel Disable Signal Circuit Low	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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