OBD-II code · Network
U02A2 Lost Communication With Reductant Quality Module
The vehicle bus reports loss of communication with the reductant (DEF/AdBlue) quality sensor module. The SCR system cannot verify urea concentration; emissions countermeasures may activate.
Is it safe to drive with U02A2?
The car may go into limp mode (reduced power). Get it diagnosed before a long trip.
Common causes
- Most likelyBus wiring open or shorted
- PossibleModule without power or ground
- PossibleModule failed
Symptoms
- Multiple warning lights may illuminate
- Affected modules may go into limp mode or shut down
- Specific functions inoperative depending on module
- Diagnostic tools may show communication faults
Repair at a glance
- Difficulty
- Medium
- DIY friendly
- Best left to a mechanic
- Typical labour
- 0.5–3 h
- Emissions test
- Likely to fail
- After the fix
- A drive cycle is needed before the light stays off
- Parts involved
- Reductant Quality Module, Vehicle Bus Wiring
Related codes
- U029FLost Communication With Evaporative Emission System Leak Detection Control Module
- U02A0Invalid Data Received From Hybrid/EV Battery Interface Control Module D
- U02A1Lost Communication With NOx Sensor C
- U02A3Lost Communication With Particulate Matter Sensor
- U02A4Lost Communication With NH3 Sensor
- U02A5Lost Communication With Reductant Heater Control Module
Code data: OBDex open dataset (CC0). Labour times are typical ranges, not a quote.