P0B34High Voltage Service Disconnect Circuit Performance
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- Can trigger limp mode
- How the car detects it
- P0B34 covers a plausibility fault of the service disconnect detection: the signal is electrically within limits but does not match what the controller expects, for example a plug reported as removed while the high-voltage bus still shows voltage, or a state that changes without a matching event. Audi lists P0B3400 in the controller at address 008C of the 2025 Q5 e-hybrid, together with U029A00 and U059B00, and asks technicians to log the case in its pending service database; no threshold is published. CARB requires hybrid components to be checked for rationality as input devices. Pure circuit, low, high and open faults are P0B33, P0B35, P0B36 and P0B37. The car may refuse ready mode or charging.
- What you may notice
- Electrical system or high-voltage warning
- No ready mode or charging interrupted
- Related network codes stored at the same time
- Likely causes
- PossibleBattery controller software fault (Audi case under investigation)
- PossibleLoose plug or worn contacts giving an implausible detection state
- PossibleIncreased resistance in the detection loop
- RareCommunication fault between battery controller and other modules
- Inspection (ITP)
- Matters for the ITP. While the check-engine light is on, the car fails the emissions check.
- Repair
- Workshop only · Usually a job for a workshop.Typical cost: €80 – €1,500
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.