Fault Family System: Powertrain (P-Codes) 8 SAE Codes

Throttle Fuel Inhibit Circuit

Diagnostic & Technical Explanation

P218B (Throttle/Fuel Inhibit B Circuit) covers the secondary throttle/fuel inhibit switch circuit used on some drive-by-wire systems as a redundant check that fuel delivery should be cut when the throttle is fully closed. An open or shorted circuit at this switch, a switch contact that has worn or become misadjusted, and corrosion at its connector are the typical causes distinguishing this from a fault in the primary throttle position sensor.

These 8 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 8 times.

Codes in this family (8)

Code	Definition	Repair coverage
P218B	Throttle/Fuel Inhibit B Circuit	3 ranked fixes
P218C	Throttle/Fuel Inhibit B Circuit Range/Performance	3 ranked fixes
P218D	Throttle/Fuel Inhibit B Circuit Low	3 ranked fixes
P218E	Throttle/Fuel Inhibit B Circuit High	3 ranked fixes
P2552	Throttle/Fuel Inhibit A Circuit	3 ranked fixes
P2553	Throttle/Fuel Inhibit A Circuit Range/Performance	3 ranked fixes
P2554	Throttle/Fuel Inhibit A Circuit Low	3 ranked fixes
P2555	Throttle/Fuel Inhibit A 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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