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P26A4

Engine Coolant Bypass Valve A Position Sensor Circuit

The position sensor on the coolant bypass valve A returns no usable signal. Closed-loop control of bypass position is lost.

  • Check engine light: Yes
  • Emissions related: No
  • Repair difficulty: medium

Common causes

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

  • Open sensor elementCommon
  • Corroded sensor connectorPossible

Parts involved

  • Bypass Position Sensor A
  • Wiring Harness

P26A4 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.