U0544 Moderate Generic / SAE

U0544: Invalid Data Received From Parking Assist Control Module B

Network and Communication Invalid Data Received (continued)

What to do

The car drives normally. Assume the parking sensors are not working and use your mirrors — the risky failure here is not constant beeping but silence, where the system has quietly stopped seeing things and you keep trusting it.

Wash the bumpers and look closely at the small round sensor faces. Mud, ice, snow, wax or a sticker over one is enough, and cleaning it is often the whole repair.

Two things worth mentioning. Has the car been repainted or had bumper work? Paint over a sensor face changes how it hears its own echo. And is there a towbar or bike rack fitted? A towball sits right in the rear sensors' view; most cars can be configured to allow for it, and one fitted without that configuration causes exactly this.

What this code means

Parking assist control module B is broadcasting data that cannot be accepted as true. See U0400 for what an invalid-data code is and why the module it names is usually the messenger rather than the culprit.

The letter is the part of this code that actually tells you something, and it is worth reading carefully.

The standard letters each instance of a repeated module — one per door, one per seat, one per window — so the letter narrows a whole-vehicle fault to one corner of the car before anybody lifts a trim panel. What the letter does not do is say which corner, because the mapping from letter to physical position is the manufacturer's to choose and it is not consistent between makes.

Only the vehicle's own documentation resolves the letter to a location. Guessing costs a stripped door card and proves nothing.

Two practical consequences. If several letters in the same family are stored together, the fault is upstream of all of them — a shared supply, a shared earth, or the bus itself — and chasing one door is wasted work. And if exactly one letter is stored, you have been handed the most valuable diagnostic fact available: the other instances are working, so everything they share is proven good.

Parking sensors fail in a way that is worth understanding, because the failure can be silent and the driver keeps trusting them.

Ultrasonic sensors work by timing an echo. Anything that muffles or blocks the face of a sensor changes that timing — mud, ice, snow, a thick coat of wax, a sticker, or the film left by a poor respray. All of them produce readings the module rejects, from sensors that are perfectly good underneath.

Which is why the first action is to wash the bumper and look at the sensor faces, and the second is to ask whether the car has been repainted or had bumper work.

The genuinely dangerous failure mode is the false negative — a system that has quietly stopped detecting rather than one that beeps constantly. A driver who has learnt to trust the beeps reverses into something the sensors no longer see. Assume the system is off until it is confirmed working.

Towbars and bike racks appear here as they do at U0533, since a permanently-mounted towball sits directly in the rear sensors' field and reads as an obstacle. Many vehicles have a configuration for that; a towbar fitted without it produces constant false alarms and, eventually, codes.

Likely causes

Start here

Corroded or loose connector · easy
Damaged data bus wiring · moderate
Radar sensor obstructed by dirt or snow · easy

Less common

Module not coded to the vehicle · specialist
Water ingress into module · moderate
Damaged wiring harness · moderate
Aftermarket fitting obstructing the radar sensor · easy

Symptoms

Components involved

Information, not instruction

CarGeek is a reference, not a service manual. Its pages are written from public sources and from what other people have found, never from a manufacturer's own service information, so they can be wrong or incomplete for your particular vehicle. Some of what they describe carries real risk: high voltage, fuel under pressure, stored energy, hot and moving parts.

Have anything you intend to act on checked by a trained person against the manufacturer's own procedure for your vehicle. Nothing here replaces that procedure.

Community experience

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