Cause
Codes cleared from one module but not the other
Fault codes cleared in one module while a related module retains its own record, so the two now disagree about whether anything is wrong. It is a diagnostic artefact rather than a vehicle fault, and it wastes a great deal of time because the surviving code describes an event that has already been repaired.
It happens because clearing is not global. Many tools clear only the module currently addressed, and a generic tool may clear only emissions-related codes from the engine module while transmission, chassis and body modules keep theirs. So a stored code can be a historical record of something fixed weeks ago, still being reported by a module nobody re-addressed.
Freeze frame and status flags are what settle it. A code marked historical or passive, with a frame naming conditions the vehicle has not seen since, is old news; one marked current is live. Clear everything from every module and drive the vehicle, then read again — what comes back is real and what does not was residue. Do this before diagnosing, not after, since it costs minutes and removes the possibility of chasing a repaired fault.
Typically an easy fix. Often worth checking before paying anyone to look.
Codes this can cause (4)
Codes where this is a likely explanation first, rather than merely a possible one.
- P0700 Transmission Control System (Malfunction Indicator Lamp Request) Moderate
- P0800 Transfer Case Control System (Malfunction Indicator Lamp Request) Moderate
- P0A7B Battery Energy Control Module Requested Malfunction Indicator Lamp Illumination Moderate
- P0AC4 Hybrid/EV Powertrain Control Module Requested Malfunction Indicator Lamp Illumination Moderate
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