GUIDE / OBD-II
Pending, confirmed and permanent codes
A pending code can reflect an initial failed monitor; a confirmed code has met the module's confirmation criteria. Where supported, permanent emissions codes normally clear after the vehicle's monitor verifies the repair, not simply with an erase command. Conditions differ by vehicle and jurisdiction. A stored code alone does not prove the fault is active now.
Before replacing a part
Record codes and freeze-frame data. Check battery condition, related codes and visible wiring or hose damage. Follow the vehicle's diagnostic procedure and test results before replacing parts.
Scan worksheet →Source-backed code explanations
Sources and interpretation
Read the meaning first, then follow the cited manufacturer pages. The explanations and vehicle-specific examples have different scopes; verify the exact application before using a repair instruction.
- 2017 MY OBD System Operation Summary for Diesel Engines — revision July 29, 2016 ↗
Ford Motor Company · PDF 201, 202
Ford 2017 diesel diagnostic-executive example: pending, confirmed and permanent DTC setting/erasure, including monitor-dependent exceptions. Page 202 also documents EWMA confirmation behavior. Applies to engines and programs covered by this manual, not every OBD-II vehicle; avoid a universal two-trip rule.
- On-Board Diagnostic Test Reference — Section C, Permanent diagnostic trouble code standards ↗
California Bureau of Automotive Repair
California Smog Check reference: supported permanent DTCs survive scan-tool clearing and battery disconnection and are removed by the OBD system after verification. Model-year support and inspection exceptions are California-specific; this guide does not prescribe those local pass/fail limits.