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P24CF

Reductant Tank Cap Switch Circuit Intermittent or Erratic

Same as P24CB with intermittent or erratic signal. Wiring faults of this kind typically come from chafing, water ingress at connector seals, or pin push-back — a wiggle test on the harness while the code is active often confirms the location.

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

Symptoms

  • Check engine light or NOx warning on
  • AdBlue/DEF level or quality warning
  • Possible no-start countdown after ignore period
  • Failed emissions inspection (NOx)

Common causes

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

  • Intermittent contact at connectorCommon
  • Connector with intermittent contact under vibrationLess likely
  • Harness routed against vibrating componentLess likely

Parts involved

  • Reductant Tank Cap Switch

P24CF 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.