Powertrain, generic (extended)

P26E2 Fuel Mode Indicator Lamp Control Circuit Low

Check engine lightUsually off
EmissionsNot relevant
Drive cycleNot required
Limp modeNo

Bi-fuel vehicles show the active fuel with an indicator, often a lamp in the selector switch. GM's 2015 Impala bi-fuel lights it while running on CNG and flashes it during a fuel change; GM's 2016 CNG pickups also flash it fast to signal a gas system fault, and Ford's earlier bi-fuel trucks combined the ALT/GAS selector with its lamp in one assembly. P26E2 means the controlling module reads the lamp control circuit as too low. Where the module switches the lamp on the positive side, that typically points to a short to ground in the wire or the lamp; with a ground-side driver the same reading can mean an open path. No manufacturer documents P26E2 publicly. The fuel change itself still works, but the driver may see a lamp that is dark or always lit and loses the fault warning. P2668 is the general circuit fault.

Likely causes

Lamp control wire chafed to ground
Shorted LED or bulb in the fuel selector switch
Faulty lamp output in the controlling module

Symptoms

  • Fuel mode lamp dark or permanently lit
  • No visible warning when the gas system has a fault

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 lampinstrument clusterwiring harness

Related codes

P26E3P2668P25A4

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