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

TCM Engine Speed Signal Circuit

Diagnostic & Technical Explanation

Code P0725 (Engine Speed Input Circuit) sets when the TCM loses or receives an implausible engine speed signal (input from the ECM) or cannot correctly output its own re-broadcast engine speed signal to other modules. Causes are a network wiring fault between ECM and TCM, a corroded connector, or a failed driver circuit inside one of the modules.

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
P0725	Engine Speed Input Circuit	3 ranked fixes
P0726	Engine Speed Input Circuit Range/Performance	3 ranked fixes
P0727	Engine Speed Input Circuit No Signal	3 ranked fixes
P0728	Engine Speed Input Circuit Intermittent	3 ranked fixes
P0737	TCM Engine Speed Output Circuit	3 ranked fixes
P0738	TCM Engine Speed Output Circuit Low	3 ranked fixes
P0739	TCM Engine Speed Output 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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