P0403 Exhaust Gas Recirculation Circuit Malfunction

P0403 points to an EGR circuit malfunction. The control module detected a problem in the electrical path that commands or monitors the EGR system.

Code status

Needs verification

Not yet verified against SAE J2012_202509 / J2012DA. Treat unverified rows as a lookup aid, not repair authority.

System
Emissions
Scope
iso-sae-controlled-p0
Standard
SAE J2012 / ISO 15031-6
Source
legacy-import

Diagnostic boundary

A diagnostic trouble code reports that a monitored test failed. It does not prove one specific part is bad, and manufacturer logic can add vehicle-specific conditions.

Do not diagnose EGR flow first when the code names the circuit; prove the electrical path before cleaning or replacing flow components.

Useful checks before replacing parts

Related OBD-II codes

These nearby emissions entries can help compare wording and fault area. They may share the same verification status as the source database.