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P20D6

Exhaust Aftertreatment Fuel Injector B Stuck Closed

Exhaust Aftertreatment Fuel Injector B Stuck Closed: the control module has detected this fault condition. This injector doses fuel into the exhaust to raise temperature for diesel particulate-filter regeneration; it does not fuel the engine.

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

Symptoms

  • Check engine light on
  • Misfire or rough idle on the affected cylinder
  • Increased fuel consumption
  • Possible fuel smell or smoke from exhaust

Common causes

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

  • Injector stuck closedCommon
  • Carbon or debris buildup preventing free movementLess likely
  • Component wear with age - mechanical playLess likely

Parts involved

  • Aftertreatment Fuel Injector

P20D6 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.