U02A3 code meaning
Lost Communication With Particulate Matter Sensor
Network system Generic code U02xx codes Check engine light
What U02A3 means
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.
U02A3 at a glance
- Check engine lightYes, usually on
- Emissions testCan fail
- Limp modePossible
- Repair difficultyMedium
- Typical labor0.3 to 2.5 hours
- Clears after repairAfter a drive cycle
Symptoms of U02A3
- MIL on
- Particulate filter monitor not completed
- Derate or inducement warning on some trucks
Common causes of U02A3
- Most likelyWrong particulate sensor variant fitted during repair
- PossibleChafed harness, blown fuse or corroded connector at the sensor unit
- PossibleEngine control software with start-up timing fault
- Less likelyParticulate sensor control unit internally failed
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
Pm sensorVehicle bus wiring
What each part of U02A3 means
| U | Network system: communication between the control modules (CAN bus). |
| 0 | Generic code: it means the same on every make (SAE standard). |
| A3 | The exact fault in that area. |
What to do next
- Note U02A3 and any other codes stored with it: several codes together often point to one cause.
- Check for loose connectors and damaged wiring around the parts the code names.
- Check open recalls for your car: some faults are fixed for free by the dealer. Enter your VIN.
- Clear the code only after the repair. If it comes back, the fault is still there.
Buying a used car? Scan it for stored codes before you pay. A recently cleared memory can hide a problem.
Questions about U02A3
What does U02A3 mean?
U02A3 means "Lost Communication With Particulate Matter Sensor". 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. It is a generic code, so it means the same on every make.
Is it safe to drive with U02A3?
Drive gently and only to a workshop. With U02A3 the car can go into limp mode (reduced power) to protect itself.
Will U02A3 fail an emissions test?
Yes, it can. U02A3 is emissions-related, so most inspection programs fail a car while it is stored or while the check engine light is on.
How hard is U02A3 to fix?
Difficulty: medium. A typical repair takes 0.3 to 2.5 hours of work. This is a job for a workshop.
Will U02A3 clear itself after the repair?
After the repair the car has to complete a drive cycle (a mix of city and highway driving) before the test runs again. Until then the readiness monitor shows "not ready", which can fail an inspection.