OBD-II code · Powertrain (generic)
P05B9 Restraint Deployment Signal Circuit Low
Same as P05B8 with the signal shorted to ground. Wiring faults of this kind typically come from chafing, water ingress at connector seals, or pin push-back — a wiggle test on the harness while the code is active often confirms the location.
Is it safe to drive with P05B9?
Usually safe to drive in the short term. Get it diagnosed when convenient, sooner if the car drives differently.
Common causes
- Most likelySignal shorted to ground
- Less likelyConnector pins corroded - high contact resistance
- Less likelyHarness chafing through insulation
Repair at a glance
- Difficulty
- Medium
- DIY friendly
- Best left to a mechanic
- Typical labour
- 0.6–2 h
- Emissions test
- Usually unaffected
- Parts involved
- Restraint Signal Wiring
Code data: OBDex open dataset (CC0). Labour times are typical ranges, not a quote.