Powertrain, generic (extended)

P25D8 Fuel Level Sensor C Performance

Check engine lightOn
EmissionsRelevant
Drive cycleRequired
Limp modeNo

P25D8 says that the third fuel level input delivers an electrically valid signal whose behaviour is not believable: it jumps, drifts or disagrees with the fuel actually used or transferred. A sender frozen at one value has its own code, P25DC, so P25D8 covers the remaining plausibility faults. No manufacturer documents P25D8 publicly. Comparable checks exist for the second sender: Ford treats more than 100 changes of over 40 % between samples taken every 0.1 s as a noisy signal (P2066), and GM's 2020 dual-tank logic checks whether the secondary sender reacts when its transfer pump moves fuel. A C-side check would likely follow similar ideas. CARB requires such rationality monitoring for fuel level inputs. The driver may see an erratic gauge or a range estimate that makes no sense.

Likely causes

Worn or dirty resistor track in sender C giving jumps
Transfer pump or line fault so the level in tank C does not change as expected
Damaged or loose float on sender C

Symptoms

  • Fuel gauge jumps or shows unrealistic values
  • Range estimate inconsistent
  • Check engine lamp on after repeated detection

Repair estimate

DifficultyMediumDIY possible
Parts and labour€100–650
Time1–3 h

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

Parts involved

fuel level sensor cfuel tank

Related codes

P25D7P25DCP2066P0461

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