Powertrain, generic (extended)

P25F2 Turbocharger/Supercharger Boost Sensor C Circuit

Check engine lightOn
EmissionsRelevant
Drive cycleNot required
Limp modePossible

A third boost pressure sensor, C, only makes sense on engines with several charging stages or chargers – for example a supercharger feeding a turbocharger, or a two-stage turbo system – where pressure is measured between the stages as well as ahead of the throttle. Which location carries the letter C is up to the manufacturer. P25F2 is the general circuit fault of this sensor, without separating low, high or implausible signals (those are P25F3 to P25F5); a networked sensor C would report lost communication as U060D instead. No manufacturer documents P25F2 publicly. For sensor A, GM-built Saab engines check the circuit all the time while the ignition is switched on and fall back to mechanical base boost with a clear loss of power, which is the likely reaction here as well.

Likely causes

Loose, corroded or oily connector at boost sensor C
Signal, 5 V reference or ground wire damaged
Boost sensor C failed internally

Symptoms

  • Check engine lamp on
  • Reduced power, boost limited to base level

Repair estimate

DifficultyMediumDIY possible
Parts and labour€60–400
Time0.5–2 h

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

Parts involved

boost pressure sensor cwiring harness

Related codes

P25F3P25F4P25F5U060DP0235P0239

References: law.cornell.edu, saabwisonline.com, en.wikipedia.org, en.wikipedia.org.