Faulty door switch or door latch assembly with an integrated switch; Damaged or chafed wiring in the door jamb boot between the body and the door; Corroded or loose connector at the door switch or body control module; Water intrusion into the door switch or connector causing intermittent shorts; Failed body control module (BCM) or door control module not interpreting the switch signal correctly; Aftermarket alarm or remote start installation tapping into the door switch circuit; Low battery voltage or poor ground causing the module to misread switch data

DTC codes / U05xx · Network communication / U0518

U0518Invalid Data Received From Door Switch C

Q: What does code U0518 mean?

Invalid Data Received From Door Switch C. U0518 means the module that monitors the door switch circuit (often the body control module) received data from the door switch that it considers invalid or out of range. The computer detected a signal that does not match any legitimate door-open, door-closed, or switch-state value, so it flags the circuit as unreliable.

U0518 means the module that monitors the door switch circuit (often the body control module) received data from the door switch that it considers invalid or out of range. The computer detected a signal that does not match any legitimate door-open, door-closed, or switch-state value, so it flags the circuit as unreliable.

SystemNetwork

Code typeGeneric (all makes)

SeverityLow

Fix difficultyIntermediate

AreaNetwork communication

Symptoms you may notice

Often no symptoms besides the warning light
Door ajar warning staying on or flickering when the door is fully closed
Interior dome light not turning on or staying on after the door is shut
Key-in-ignition or headlight-on chime behaving erratically
Remote keyless entry or push-button start intermittently failing to recognize a door state
Battery drain from a module staying awake because it thinks a door is open

Common causes, most likely first

Faulty door switch or door latch assembly with an integrated switch
Damaged or chafed wiring in the door jamb boot between the body and the door
Corroded or loose connector at the door switch or body control module
Water intrusion into the door switch or connector causing intermittent shorts
Failed body control module (BCM) or door control module not interpreting the switch signal correctly
Aftermarket alarm or remote start installation tapping into the door switch circuit
Low battery voltage or poor ground causing the module to misread switch data

How to diagnose and fix it

Verify battery voltage and charge or replace the battery if it is below 12.4 volts at rest
Inspect the door jamb wiring boot for chafed, broken, or corroded wires and repair as needed
Disconnect and inspect the door switch connector for corrosion, water, or loose pins; clean and reseat
Test the door switch with a multimeter for continuity in open and closed positions, replacing the switch if it does not switch cleanly
Check for aftermarket accessories spliced into the door switch circuit and remove or repair poor connections
Use a scan tool to view door switch data in the body control module and compare it to actual door position
If the switch and wiring test good, check for body control module software updates or replace the module as a last resort

Door switch data faults that fool technicians

A door switch that tests fine with a multimeter can still send invalid data intermittently because the fault is in the latch mechanism or the module's interpretation of a marginal signal.
The door jamb wiring boot is a common failure point that gets overlooked because the damage is hidden inside the rubber boot and only shows up when the door is opened or closed.
Aftermarket alarm or remote start wiring spliced into the door switch circuit often introduces resistance or noise that the body control module flags as invalid data.
U0518 can be set by a low battery or poor ground even when the door switch itself is perfect, because the module misreads voltage levels during cranking or low-voltage events.
A door switch that is mechanically worn can produce a signal that looks correct on a meter but changes state too slowly for the module, which then rejects the data as invalid.

Can I keep driving with U0518?

The vehicle remains safe to drive because the fault affects convenience and monitoring functions rather than engine or brake operation. Avoid leaving the vehicle parked for long periods until the fault is repaired, since a module that thinks a door is open can drain the battery.

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.