Powertrain, generic · Computer and auxiliary outputs

P06A6 Sensor Reference Voltage A Circuit Range/Performance

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. P06A6 is the range/performance check of reference circuit A: the voltage is outside a narrow window without being split into low and high. Ford uses it: its 2012 and 2020–23 petrol tables flag below 4.7 V or above 5.2 V for 0.5 s (Bosch modules), and the 2023 diesel below 4.7 V or above 5.3 V for 5 s, where supply 1 feeds the rail pressure and crankshaft sensors. In the Saab 9-4X the fuel pump control module uses it for its fuel pressure sensor supply. Expect fuel pressure or crankshaft codes and reduced power; Ford's low/high codes for circuit A are P0642/P0643.

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
  • Fuel pressure or crankshaft sensor codes as well
  • Reduced power or 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

P0641P0642P0643P06A7P0191P0335

References: law.cornell.edu, newtonnet.co.uk, fordservicecontent.com, fordservicecontent.com.