Stored (confirmed) code
Definition
A stored or confirmed code is a fault the ECU has verified according to its detection strategy, usually by failing on two consecutive trips (or immediately for serious one-trip faults such as catalyst-damaging misfires), and it is reported in Mode 03 along with the MIL request. The code stays stored until it is cleared with a scan tool or until the fault has been absent for 40 warm-up cycles, while the MIL itself goes out after three consecutive fault-free trips. Scan tools often label it active (fault present now) or history/intermittent (fault was present earlier), which is critical for deciding whether you are chasing a live problem or an old event; manufacturer tools add frequency counters and mileage since first and last occurrence. Read the freeze frame and the pending list before clearing, and never clear codes before an emissions test because readiness monitors reset too. Any DTC can be stored: P0300 misfire and P0420 catalyst efficiency are the classic examples, as are U0100-series communication codes and chassis codes such as C0035.