Theft deterrent fuel enable signal not received
What it means
P1629. Theft deterrent fuel enable signal not received. Engine computer never got the start password. This Chevy-enhanced code applies to Silverado, Sierra, Tahoe, Suburban 1999 to 2006. Impala, Malibu, Cavalier with Passlock..
Findings, check these first
- Faulty Passlock sensor in lock cylinder
- Damaged Passlock wiring
- Faulty body control module
- Faulty powertrain control module
- Aftermarket remote start interference
Standard procedure
- Try spare key and watch security light
- Inspect Passlock sensor wiring
- Test with proper theft relearn procedure
- Remove suspect aftermarket wiring
- Replace lock cylinder sensor if it fails
Look up another code
Press / to jump to the box. Chevy-enhanced powertrain, body, chassis and network codes.
Sources and review
Review: checked against the recorded source material.
- P1629 CADILLAC Theft Deterrent Start Enable Signal Not Received | AutoCodes
archived reference page (autocodes.com via Wayback Machine)
Supports: code identity and GM application
Fetched directly. Cadillac GM page names a theft deterrent start enable signal not received, the same enable-signal meaning as the catalog.
- OBDII Code P1629 CHEVROLET - Theft Deterrent System - Cranking Signal | Engine-Codes.com
archived reference page (engine-codes.com via Wayback Machine)
Supports: code identity and Chevrolet application, with cranking signal wording
Fetched directly. The Chevrolet page uses the cranking signal wording for the same theft deterrent code.
Last updated 2026-09-25.
Report a correction for P1629. Include your vehicle, the issue and a source if you have one.
This fault sits in the GM theft deterrent system. The GM security codes and Passlock relearn guide covers the families and the relearn cycles.