P0604 on GMC vehicles

A model year is listed because the code is named in its own record — a bulletin filed against it, or an owner’s complaint about it — not because every one of these vehicles sets it. Counts are documents in NHTSA’s files, not failure rates.

Bulletins and campaigns GMC filed with NHTSA whose summary names P0604. Quote the document number at the service desk — it is a diagnosis the maker has already written down.

• PIT6512 Service bulletin
  2026-05-11 · Unknown Or Other
• This PI states that if SDGM DTC P0604/P0607 is set and no other SDGM DTCs are present, clear DTCs and reset the SDGM. Advises of how to contact PQC to authorize SDGM replacement.
• PIT6512A Service bulletin
  2026-08-03 · Unknown Or Other
• This PI states that if SDGM DTC P0604/P0607 is set and no other SDGM DTCs are present, clear DTCs and reset the SDGM. Advises of how to contact PQC to authorize SDGM replacement.

A stored code names the test that failed, never the part that caused it. The record above is what GMC and its owners have filed about it; the code’s page across every make has the whole file.