P1629 — Theft Deterrent — Start Enable Signal Not Received
STOPIs it safe to drive? Don’t keep driving — risk of real damage or a safety issue.
What P1629 means
This is a manufacturer-specific code — its meaning depends on the vehicle’s make (see below).
What P1629 means on specific makes
Chevy / GMC / Cadillac / Buick STOP
The PCM never got the start-enable signal from the anti-theft system at all (vs P1631 where it's received but wrong). Causes a no-start/stall. Same PassLock/BCM family of causes.
- BCM-to-PCM data line fault ($50-300)
- PassLock sensor failure ($100-250)
- Failed BCM ($200-500)
- Relearn needed ($0)
Check first: Verify Class-2 data communication between BCM and PCM; attempt PassLock relearn; check the PassLock sensor.
Source: engine-codes.com P1629 / aa1car