A faulty door switch B itself, such as a worn latch switch, stuck plunger, or corroded contact inside the door latch assembly.; Damaged or chafed wiring in the door jamb harness, where the flexible boot flexes every time the door opens and closes.; Corroded or loose connector pins at the door switch, the door module, or the body control module (BCM) that reports the switch state.; A failing body control module or door control module that has stopped transmitting the door switch status on the CAN bus.; Water intrusion into the door, sill, or footwell area that corrodes connectors and splices in the door switch circuit.; A blown fuse or poor ground shared by the door switch circuit or the module that reads it.; Aftermarket accessories, alarms, or remote starters tapped into the door switch wiring and disturbing the signal.

DTC codes / U02xx · Lost communication with a control module / U0216

U0216Lost Communication With 'Door Switch B'

Q: What does code U0216 mean?

Lost Communication With 'Door Switch B'. U0216 is a generic communication fault that sets when a control module on the vehicle's Controller Area Network (CAN) bus stops receiving messages from the module responsible for 'Door Switch B', which is typically a door ajar, latch, or courtesy switch input. The detecting module has lost the expected periodic data from that switch or the module that reports it, so it flags a lost communication fault rather than a circuit fault.

U0216 is a generic communication fault that sets when a control module on the vehicle's Controller Area Network (CAN) bus stops receiving messages from the module responsible for 'Door Switch B', which is typically a door ajar, latch, or courtesy switch input. The detecting module has lost the expected periodic data from that switch or the module that reports it, so it flags a lost communication fault rather than a circuit fault.

SystemNetwork

Code typeGeneric (all makes)

SeverityLow

Fix difficultyIntermediate

AreaLost communication with a control module

Symptoms you may notice

The warning light (check engine or service vehicle soon) illuminates with no obvious change in how the vehicle drives.
Often no symptoms besides the warning light, especially if the affected door switch only feeds convenience features.
Interior dome or courtesy lights stay on, fail to come on, or behave erratically when a door is opened.
The driver information display may show a door ajar message for a door that is fully closed, or fail to show it when open.
Keyless entry, door lock/unlock, or remote start functions may work intermittently or not at all.
The vehicle may fail to enter sleep mode, causing a parasitic battery drain over a few days.

Common causes, most likely first

A faulty door switch B itself, such as a worn latch switch, stuck plunger, or corroded contact inside the door latch assembly.
Damaged or chafed wiring in the door jamb harness, where the flexible boot flexes every time the door opens and closes.
Corroded or loose connector pins at the door switch, the door module, or the body control module (BCM) that reports the switch state.
A failing body control module or door control module that has stopped transmitting the door switch status on the CAN bus.
Water intrusion into the door, sill, or footwell area that corrodes connectors and splices in the door switch circuit.
A blown fuse or poor ground shared by the door switch circuit or the module that reads it.
Aftermarket accessories, alarms, or remote starters tapped into the door switch wiring and disturbing the signal.

How to diagnose and fix it

Connect a scan tool and read all modules for stored codes, then record which module set U0216 and whether other communication codes are present.
Inspect the door jamb wiring boot and the door switch connector for chafing, corrosion, or pushed-out pins, and repair as needed.
Test the door switch B circuit with a multimeter for continuity and correct open/closed state changes while operating the door.
Check the fuse and ground for the door switch circuit and the module that reports it, cleaning or replacing as required.
If the switch and wiring test good, perform a network communication test to confirm the reporting module is alive on the CAN bus.
Substitute a known-good door switch or module only after circuit tests, then clear codes and verify U0216 does not return after a road test.
If the fault persists, check for water intrusion and inspect the body control module connectors for corrosion before condemning the module.

Door switch faults that mimic module failure

A door switch B fault often sets because the latch assembly is dirty or dry, not because the switch has failed electrically, so cleaning and lubricating the latch can cure the code.
The code can be stored by a module that never sees the switch directly, so the fault may live in the body control module or a door module rather than at the door itself.
Chafed wires inside the door jamb boot are a common hidden cause that only shows up when the door is moved through its full swing, so wiggle-test the harness while watching live data.
A weak or failing battery can cause multiple modules to drop off the bus and set communication codes like U0216, so always check battery voltage and ground quality first.
Aftermarket alarms and remote starters spliced into the door switch wire frequently disturb the signal and set this code even when the factory parts are healthy.

Can I keep driving with U0216?

The vehicle is generally safe to drive because U0216 affects convenience and communication rather than engine, steering, or braking control. Avoid leaving the vehicle parked for long periods until it is repaired, since a door switch fault can prevent the modules from sleeping and drain the battery.

Tools that help

Tools we recommend are in the Auto Veteran shop on Amazon. As an Amazon Associate we earn from qualifying purchases.

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