Powertrain, generic · Computer and auxiliary outputs

P06A4 Sensor Reference Voltage D Circuit Low

Check engine lightOn
EmissionsRelevant
Drive cycleNot required
Limp modePossible

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.

Likely causes

Short in the wire or sensor of a connected sensor
Chafing or water in harness or connector
A connected sensor faulty internally
Module internal voltage regulator

Symptoms

  • Check engine light
  • Several sensor codes at once (pedal, throttle, pressure)
  • Electronic throttle limp mode, reduced power
  • Possibly starting problems

Repair estimate

DifficultyMediumWorkshop job
Parts and labour€80–600
Time1–3 h

Typical range across vehicles; the real cost depends on what the testing finds.

Parts involved

sensor reference voltage circuitsensor wiringengine control module

Related codes

P06A3P06A5P0698P0642P2122

References: law.cornell.edu, gsi.ext.gm.com, saabwisonline.com.