Powertrain, generic (extended)

P25A5 Fuel Mode Select Switch Performance

Check engine lightOn
EmissionsRelevant
Drive cycleNot required
Limp modeNo

P25A5 flags a performance problem with the fuel mode select switch. The circuit is electrically sound, yet the switch behaves in a way that cannot be genuine, such as a momentary button that appears to be held down for minutes or a press that never returns to rest. On GM's bi-fuel trucks the chosen mode is kept across key cycles and each press toggles the fuel, so a stuck contact would keep requesting changes; GM's material on the bi-fuel Impala of 2015 notes that the switch light flashes while a fuel transition is under way. No manufacturer documents P25A5 publicly. Likely culprits are spilt drinks in the centre stack, a cap jammed after trim work or a switch from the wrong variant. The driver may lose manual fuel selection while the engine runs on.

Likely causes

Switch button sticking or contaminated by liquid
Panel trim pressing on the switch after installation work
Replacement switch of the wrong type or coding

Symptoms

  • Fuel mode changes by itself or not at all
  • Switch indicator keeps flashing

Repair estimate

DifficultyEasyDIY possible
Parts and labour€30–250
Time0.3–1.5 h

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

Parts involved

fuel mode switch

Related codes

P25A4P25A6P25A7P25A8

References: static.nhtsa.gov, gmc.com.