U016D: Lost Communication With Exhaust Gas Sensor Module B

What it means

ECU lost CAN communication with exhaust gas sensor module B (often integrates wide-range O2/NOx sensors).

At a glance

• Usually lights the warning light of the system that lost communication
• Affects emissions; the car can fail an emissions test

How it works

Exhaust Gas Sensor Module B collects or processes exhaust-sensor information, which may include wide-range oxygen or NOx sensor data, and sends it to other modules over CAN. U016D sets when the reporting module does not receive the expected messages from that specific exhaust sensor module.

Common causes

Most likely first.

1. Module unpowered
2. Gateway module routing CAN messages incorrectly
3. CAN terminating resistor (120 Ω) drifted out of spec

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

How to diagnose it

1. Scan all modules for communication and emissions codes, and save freeze-frame data to identify whether the fault occurred during a particular engine operating condition.
2. Check whether Exhaust Gas Sensor Module B responds to a scan tool and whether related sensor readings disappear from live data.
3. Inspect module B’s connectors and wiring, especially sections exposed to exhaust heat, road debris, or moisture.
4. Check its fuses, power, and ground according to the manufacturer's specification.
5. If supplies are correct, test the CAN wiring and termination, then investigate gateway routing or a failed module.

Common fixes

• Secure or clean a loose or corroded module B connector.
• Repair heat-damaged or broken wiring to the exhaust gas sensor module.
• Restore a failed fuse, power feed, or ground connection.
• Repair the CAN network or gateway routing if tests identify a communication path fault.
• Replace Exhaust Gas Sensor Module B if its supplies and CAN circuit are sound.

Can I keep driving?

The engine may still run, but emissions monitoring or control can be impaired and the malfunction indicator may stay on. Avoid ignoring the warning for an extended period, since emissions faults can affect fuel economy or prevent an emissions test.