Powertrain, generic (extended)

P2E56 Exhaust Pressure Sensor C Circuit Low

Check engine lightOn
EmissionsRelevant
Drive cycleNot required
Limp modePossible

P2E56 means the signal of exhaust pressure sensor C stays under the lowest voltage a working sensor can produce. Analogue exhaust pressure sensors return a share of their 5 V reference; Ford's petrol transfer function for sensor A puts 49 kPa at 0.3 V and flags anything under 0.21 V for 5 s, while its 2023 diesels use 0.1 V for 2 s. No manufacturer publicly documents P2E56. A signal wire shorted to ground, a lost 5 V reference or a sensor with a failed output stage are the usual reasons; if several sensors on the same reference set low codes at once, the reference or the module is the better suspect. Functions that use the value, such as EGR or turbocharger control, then rely on substitute values, so power may be limited. The high-side code is P2E57, sensor A's low code P0472.

Likely causes

Signal wire of sensor C shorted to ground
5 V reference open or pulled down by another sensor
Sensor C output stage failed

Symptoms

  • MIL on
  • Possible loss of power from substitute values
  • Further low codes of sensors sharing the reference

Repair estimate

DifficultyMediumDIY possible
Parts and labour€40–350
Time0.5–2 h

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

Parts involved

exhaust pressure sensor cwiring harnessecm

Related codes

P2E57P2E54P2E55P0472P047C

References: fordservicecontent.com, fordservicecontent.com, law.cornell.edu.