U010B code meaning
Lost Communication With Exhaust Gas Recirculation Control Module B
Network system Generic code U01xx codes Check engine light
What U010B means
U010B names the second exhaust gas recirculation control module, B. Its existence implies an engine with two separately controlled EGR units, for example a high- and a low-pressure loop on a diesel or one unit per cylinder bank; which one is B is the maker's choice. The code itself only says that a node expecting periodic messages from module B no longer receives them. Neither a manufacturer document nor any entry in the NHTSA bulletin index names U010B. Diagnosis therefore follows the generic path: supply, ground and bus lines of module B first, then the module. If only B is silent while A (U010A) still talks, the fault sits in B's branch. Invalid data from B is U040C; CARB's EGR monitoring makes the code emission-relevant.
U010B at a glance
- Check engine lightYes, usually on
- Emissions testCan fail
- Limp modePossible
- Repair difficultyMedium
- Typical labor0.5 to 3 hours
- Clears after repairWhen cleared with a scanner
Symptoms of U010B
- MIL on
- Second EGR path inactive, possible NOx increase
- Module B not reachable with a scan tool
Common causes of U010B
- Most likelyEGR module B without power or ground
- PossibleOpen or chafed bus branch to module B
- PossibleLoose or heat-damaged connector at module B
- Less likelyEGR module B internally faulty
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
EGR module bCAN bus wiring
What each part of U010B means
| U | Network system: communication between the control modules (CAN bus). |
| 0 | Generic code: it means the same on every make (SAE standard). |
| 0B | The exact fault in that area. |
What to do next
- Note U010B 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 U010B
What does U010B mean?
U010B means "Lost Communication With Exhaust Gas Recirculation Control Module B". U010B names the second exhaust gas recirculation control module, B. It is a generic code, so it means the same on every make.
Is it safe to drive with U010B?
Drive gently and only to a workshop. With U010B the car can go into limp mode (reduced power) to protect itself.
Will U010B fail an emissions test?
Yes, it can. U010B 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 U010B to fix?
Difficulty: medium. A typical repair takes 0.5 to 3 hours of work. This is a job for a workshop.
Will U010B clear itself after the repair?
Clear the code with a scanner after the repair. If the fault is fixed, it does not come back.