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U02A3 Lost Communication With Particulate Matter Sensor

Check engine lightOn
EmissionsRelevant
Drive cycleRequired
Limp modePossible

The particulate matter sensor behind the diesel particulate filter collects soot on a heated element; its own control unit reports the result over CAN, and the engine controller uses it to judge the filter. U02A3 means those frames have stopped. Ford's 2023 diesel summary sets it after 7 s at 11 to 16 V. GM waits 10 s and rates it Type B. Ford's 2014 code list and FCA's Ram 2500 and 3500 bulletin 18-052-19 show it with MIL. FCA STAR case S2218000023 for the 2019 Jeep Compass explains U02A3 right after a sensor replacement by a wrong sensor variant, so compare the stamped part number. On 2023 Volvo and Mack trucks it set when the engine was cranked immediately after key on; new software followed. The filter check stays incomplete, and on trucks a derate is possible.

Likely causes

Wrong particulate sensor variant fitted during repair
Chafed harness, blown fuse or corroded connector at the sensor unit
Engine control software with start-up timing fault
Particulate sensor control unit internally failed

Symptoms

  • MIL on
  • Particulate filter monitor not completed
  • Derate or inducement warning on some trucks

Repair estimate

DifficultyMediumWorkshop job
Parts and labour€0–700
Time0.3–2.5 h

Typical range across vehicles; the real cost depends on what the testing finds.

Parts involved

pm sensorvehicle bus wiring

Related codes

U05A4U04A4P24D0P2002

References: fordservicecontent.com, gsi.ext.gm.com, static.nhtsa.gov, static.nhtsa.gov.