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P25B1

Fuel Level Sensor B Stuck

Same condition as sensor A stuck, applied to the second fuel level sensor B. Saddle tanks (often AWD vehicles) and large trucks use two sensors — one per tank chamber — averaged for total level. A stuck B leaves only A and reduces accuracy.

  • Check engine light: Yes
  • Emissions related: Yes
  • Repair difficulty: medium

Common causes

Ordered by how often each turns out to be the cause.

  • Stuck floatCommon

Parts involved

  • Fuel Level Sensor B

P25B1 is a generic OBD-II code defined by SAE J2012. Exact wording and diagnostic procedure vary by manufacturer and model. Code definitions are drawn from the public-domain OBDex dataset; the workshop notes are our own.