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P04A6

Exhaust Pressure Control Valve B Position Sensor Circuit

A circuit fault is detected on the position sensor of exhaust pressure control valve B. Without valid position feedback the ECU cannot run closed-loop control of the valve and falls back to a default substitute.

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

Common causes

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

  • Open in sensor signal, supply or groundCommon

Parts involved

  • Exhaust Pressure Position Sensor B

P04A6 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.