Fault Family System: Powertrain (P-Codes) 15 SAE Codes

EGR Position Sensor Circuit

Diagnostic & Technical Explanation

Code P0405 (EGR Sensor A Circuit Low) sets when the ECM sees an open circuit, out-of-range voltage, or an erratic/intermittent signal from the position feedback sensor (Sensor A, B, or C on multi-valve platforms) integrated into or mounted on the EGR valve. Causes are a corroded or unseated connector, a worn sensor track inside the valve assembly, or chafed wiring between the valve and the ECM.

These 15 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 15 times.

Codes in this family (15)

Code	Definition	Repair coverage
P0405	EGR Sensor A Circuit Low	4 ranked fixes
P0406	EGR Sensor A Circuit High	4 ranked fixes
P0407	EGR Sensor B Circuit Low	4 ranked fixes
P0408	EGR Sensor B Circuit High	4 ranked fixes
P0409	EGR Sensor A Circuit	4 ranked fixes
P044A	EGR Sensor C Circuit	4 ranked fixes
P044B	EGR Sensor C Circuit Range/Performance	4 ranked fixes
P044C	EGR Sensor C Circuit Low	4 ranked fixes
P044D	EGR Sensor C Circuit High	4 ranked fixes
P044E	EGR Sensor C Circuit Intermittent/Erratic	4 ranked fixes
P046C	EGR Sensor A Circuit Range/Performance	4 ranked fixes
P046D	EGR Sensor A Circuit Intermittent/Erratic	4 ranked fixes
P046E	EGR Sensor B Circuit Range/Performance	4 ranked fixes
P046F	EGR Sensor B Circuit Intermittent/Erratic	4 ranked fixes
P0486	EGR Sensor B Circuit	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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