U061B code meaning
Lost Communication With Reductant Level Sensor C
Network system Generic code U06xx codes Check engine light
What U061B means
Level sensor C is a third level input of a reductant system and exists only on layouts with more than one tank or measuring point. No manufacturer publicly documents U061B or explains which part carries the letter C. The code says that this third sensor's digital messages have stopped or keep arriving corrupted, so its reading is treated as unknown. Because CARB counts the reductant supply among the SCR functions an OBD system must watch, and asks for a separate code whenever a digital input stops communicating, the fault is emission-related even if levels A and B still report. Volvo's guide for its CAN-connected truck tank sensor starts with the harness and the pins, looking for damage, corrosion and water, which is also the sensible first step here. P21AD to P21B1 cover the circuit faults of sensor C.
U061B at a glance
- Check engine lightYes, usually on
- Emissions testCan fail
- Limp modeNot expected
- Repair difficultyMedium
- Typical labor0.5 to 3 hours
- Clears after repairWhen cleared with a scanner
Symptoms of U061B
- Malfunction indicator lamp
- Implausible DEF quantity on the display
Common causes of U061B
- Most likelyDamaged pins, corrosion or water in the connector of sensor C
- PossibleHarness to the additional tank or measuring point damaged
- Less likelyInternal failure of level sensor C
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
Reductant level sensor cSensor wiring
What each part of U061B means
| U | Network system: communication between the control modules (CAN bus). |
| 0 | Generic code: it means the same on every make (SAE standard). |
| 1B | The exact fault in that area. |
What to do next
- Note U061B 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 U061B
What does U061B mean?
U061B means "Lost Communication With Reductant Level Sensor C". Level sensor C is a third level input of a reductant system and exists only on layouts with more than one tank or measuring point. It is a generic code, so it means the same on every make.
Is it safe to drive with U061B?
Usually yes, for a short time, if the check engine light is steady and the car drives normally. If the light flashes or the car runs badly, stop and have it checked.
Will U061B fail an emissions test?
Yes, it can. U061B 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 U061B to fix?
Difficulty: medium. A typical repair takes 0.5 to 3 hours of work. This is a job for a workshop.
Will U061B clear itself after the repair?
Clear the code with a scanner after the repair. If the fault is fixed, it does not come back.