A failed or internally shorted exhaust gas sensor module B, which houses the sensor and its control electronics.; Corroded, loose, or damaged electrical connectors at the sensor module or at the control module.; Broken, chafed, or shorted wires in the CAN bus or power/ground circuits serving the sensor module.; A blown fuse or relay that supplies power to the exhaust gas sensor module.; A software or calibration issue in the control module that handles the sensor module communication.; A faulty control module (ECM or body control module) that is not properly transmitting or receiving on the CAN bus.

DTC codes / U01xx · Lost communication with a control module / U016D

U016DLost Communication With Exhaust Gas Sensor Module B

Q: What does code U016D mean?

Lost Communication With Exhaust Gas Sensor Module B. U016D is a communication fault where the engine control module (ECM) or another primary module has lost contact with the exhaust gas sensor module B over the vehicle's controller area network (CAN) data bus. The computer detects that the module responsible for monitoring and controlling a specific exhaust gas sensor has stopped reporting, which can disable that sensor's feedback and trigger the warning light.

U016D is a communication fault where the engine control module (ECM) or another primary module has lost contact with the exhaust gas sensor module B over the vehicle's controller area network (CAN) data bus. The computer detects that the module responsible for monitoring and controlling a specific exhaust gas sensor has stopped reporting, which can disable that sensor's feedback and trigger the warning light.

SystemNetwork

Code typeGeneric (all makes)

SeverityMedium

Fix difficultyIntermediate

AreaLost communication with a control module

Symptoms you may notice

Illumination of the check engine light or service engine soon light, often with no other obvious symptoms.
Reduced fuel economy as the engine control module reverts to open-loop or default fueling strategies.
A noticeable hesitation or stumble during acceleration if the affected sensor is critical to fuel trim.
Failure of the vehicle to enter closed-loop fuel control, keeping emissions high.
In some cases, a message on the driver information center stating a sensor or emissions system fault.
Intermittent warning light operation if the communication loss is due to a loose connection or chafed wire.

Common causes, most likely first

A failed or internally shorted exhaust gas sensor module B, which houses the sensor and its control electronics.
Corroded, loose, or damaged electrical connectors at the sensor module or at the control module.
Broken, chafed, or shorted wires in the CAN bus or power/ground circuits serving the sensor module.
A blown fuse or relay that supplies power to the exhaust gas sensor module.
A software or calibration issue in the control module that handles the sensor module communication.
A faulty control module (ECM or body control module) that is not properly transmitting or receiving on the CAN bus.

How to diagnose and fix it

Perform a visual inspection of the exhaust gas sensor module B and its wiring for obvious damage, corrosion, or loose connections.
Check all fuses and relays related to the exhaust gas sensor module and the CAN bus communication circuits.
Use a scan tool to read live data and confirm whether the sensor module B is communicating; check for other communication codes that might indicate a bus-wide issue.
Measure resistance and continuity on the CAN bus circuits between the control module and the sensor module to rule out open or shorted wiring.
Check for proper power and ground at the exhaust gas sensor module connector with the key on and engine off.
If wiring and power are good, substitute a known-good exhaust gas sensor module B to see if communication is restored.
If the module still does not communicate, diagnose the control module or CAN bus for internal faults, possibly requiring reprogramming or replacement.

Before you replace the sensor module

A loose or corroded ground connection at the exhaust gas sensor module can cause intermittent communication loss that mimics a failed module.
The code can be set by a low battery or charging system fault that drops voltage below the module's operating threshold during cranking.
Aftermarket exhaust work or sensor replacement can pinch or melt the sensor module wiring harness, leading to this code.
Some vehicles require a relearn or calibration procedure after replacing the exhaust gas sensor module, and skipping it can leave the code stored.
U016D can be a secondary code triggered by a primary communication fault on the CAN bus, so always check for other U-codes first.

Can I keep driving with U016D?

You can usually drive the vehicle short distances to a repair shop, but avoid heavy acceleration or long trips because the engine may run on default fuel maps, increasing emissions and potentially damaging the exhaust system. If the engine runs poorly or stalls, stop driving and have the vehicle towed.

Tools that help

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Guidance is general and written for all OBD-II vehicles. Exact tests and values vary by model, so confirm the fault before replacing parts.