P06A4Sensor Reference Voltage D Circuit Low
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- Can trigger limp mode
- How the car detects it
- The engine module feeds sensors from several regulated 5 V reference circuits; a short at one sensor pulls the whole circuit down, so all its sensors report at once – unplug them one by one to find the culprit. On GM engines (2016–2025) circuit D feeds pedal sensor 1 and both throttle position sensors, on the Saab 9-4X the throttle and pedal sensor 1 – a fault therefore usually means electronic throttle limp mode. P06A4 means reference D is too low – a short to ground or overload. No manufacturer document available to us uses P06A4 itself: GM and Saab report circuit D faults collectively as P06A3. The description follows circuits A–C.
- What you may notice
- Check engine light
- Several sensor codes at once (pedal, throttle, pressure)
- Electronic throttle limp mode, reduced power
- Possibly starting problems
- Likely causes
- LikelyShort in the wire or sensor of a connected sensor
- PossibleChafing or water in harness or connector
- PossibleA connected sensor faulty internally
- RareModule internal voltage regulator
- Inspection (ITP)
- Matters for the ITP. While the check-engine light is on, the car fails the emissions check.
- Repair
- Medium · Usually a job for a workshop.Typical cost: €80 – €600
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.