What it means
Same as P05F9 with the signal shorted to supply. 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.
At a glance
- Usually lights the check-engine light
How it works
The stop-start status signal reports whether the engine is running or automatically stopped. P05FB sets when the signal circuit voltage is higher than expected, often because the signal wire is shorted to a supply voltage or a connector is faulty.
Common causes
Most likely first.
- Signal shorted to supply
- Connector pins corroded - high contact resistance
- Supply wire pinched against B+ source
Symptoms
- Stop-start may be unavailable or operate inconsistently
- Check-engine or stop-start warning light may illuminate
How to diagnose it
- Record freeze-frame data and scan for related stop-start or communication codes to see when the high signal was detected.
- Inspect the signal harness for pinching, chafing against a power wire, water intrusion, corrosion, or pushed-back connector pins.
- Check live status data while gently moving the accessible harness and note whether the reported stop-start state changes.
- Use the wiring diagram to test for a short to supply and compare signal-circuit readings with the manufacturer's specification.
- If the circuit is sound, verify the signal source and module input connections before considering a component fault.
Common fixes
- Repair signal-wire insulation where it is contacting a supply wire.
- Clean and secure corroded or loose connector pins.
- Repair a damaged connector seal or pushed-back terminal.
- Replace a faulty status-signal source only after confirming the circuit is not shorted to supply.
Can I keep driving?
The stop-start system may be unavailable or operate inconsistently, but this code alone does not indicate that normal driving is unsafe. Watch for other warnings or engine-running symptoms and have the signal circuit checked if the fault remains.
A code shows where the control module detected a fault, not always which part failed. Check the causes in order and confirm with a test before replacing parts. Have several codes? Check them together
This is a generic code: it means the same on every make. The car’s maker may add more detail in its own service information.