U016D code meaning
Lost Communication With Exhaust Gas Sensor Module B
Network system Generic code U01xx codes Check engine light
What U016D means
U016D refers to exhaust gas sensor module B, a second smart sensor unit in the exhaust that heats a probe, evaluates it and reports oxygen or NOx readings as bus data instead of an analog voltage. Module A has U011A. Which sensor counts as B depends on the maker, for instance the other bank or a probe further downstream behind an SCR catalyst. No manufacturer documents U016D publicly, and the NHTSA bulletin index has no entry for it. CARB 13 CCR 1968.2 obliges OBD to flag a lost digital link from such an input with its own code, and exhaust and NOx sensors are emission monitors in their own right, so the MIL is normally lit. Mixture correction, catalyst checks or urea dosing may fall back to defaults. U046E is invalid data from module B.
U016D at a glance
- Check engine lightYes, usually on
- Emissions testCan fail
- Limp modeNot expected
- Repair difficultyMedium
- Typical labor0.5 to 3 hours
- Clears after repairAfter a drive cycle
Symptoms of U016D
- Check engine light on
- Readiness monitors for catalyst or exhaust sensors not complete
- Diesel: SCR or emission warning, possibly reduced power
Common causes of U016D
- Most likelySensor module connector or harness damaged by exhaust heat or corrosion
- PossibleSensor module without power or ground (fuse, relay)
- PossibleBus line to the module chafed under the vehicle
- PossibleSensor module B or integrated probe electronics faulty
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
Exhaust gas sensor module bCAN bus wiring
What each part of U016D means
| U | Network system: communication between the control modules (CAN bus). |
| 0 | Generic code: it means the same on every make (SAE standard). |
| 6D | The exact fault in that area. |
What to do next
- Note U016D 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 U016D
What does U016D mean?
U016D means "Lost Communication With Exhaust Gas Sensor Module B". U016D refers to exhaust gas sensor module B, a second smart sensor unit in the exhaust that heats a probe, evaluates it and reports oxygen or NOx readings as bus data instead of an analog voltage. It is a generic code, so it means the same on every make.
Is it safe to drive with U016D?
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 U016D fail an emissions test?
Yes, it can. U016D 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 U016D to fix?
Difficulty: medium. A typical repair takes 0.5 to 3 hours of work. This is a job for a workshop.
Will U016D 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.