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P04D2

EGR Temperature Sensor C Circuit Intermittent or Erratic

Same as P04CE with intermittent or erratic signal. EGR mixes inert exhaust into intake to lower combustion peak temperature — too little raises NOx, too much causes misfires and rough running.

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

Symptoms

  • Check engine light on
  • Pinging or knocking under load
  • Power loss and hesitation
  • Possible rough idle
  • 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

  • EGR Temperature Sensor C
  • EGR Temperature Wiring C

P04D2 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.