U0484 — Invalid Data Received From Lighting Control Module Rear "A"

U0484 — Invalid Data Received From Lighting Control Module Rear "A". A fault in the vehicle network (CAN bus) communication. Short, gentle driving to a shop is usually possible. Typical causes: damaged CAN bus wiring or short to power/ground, a faulty module pulling the bus down, water ingress in harness junctions.

vehicle network

Is it safe to drive?

Drive with caution Depends on what is affected. A single dead convenience module is fine to drive with; loss of communication with engine, braking or steering modules is not. If multiple critical systems drop out, do not drive.

How to diagnose with an OBD scanner

Read the code and freeze frame Connect an OBD2 scanner, confirm U0484 is stored, and save the freeze frame data — it shows engine conditions when the fault was detected.
Check for companion codes and TSBs Related codes often reveal the real root cause. Also check manufacturer technical service bulletins (TSB) for your make and model — many U0xxx issues have factory fixes or software updates. Search by VIN on the manufacturer site or nhtsa.gov.
Inspect wiring and connectors Visually inspect the wiring harness and connectors related to the vehicle network (CAN bus) communication for damage, corrosion, chafing or poor contact.
Subsystem check Measure resistance between CAN-High and CAN-Low at the OBD port with power off — about 60 Ω is healthy.
Subsystem check Scan all modules: the one that does not respond is either the culprit or downstream of the break.
Verify the repair Clear the code, complete a full drive cycle including the conditions from the freeze frame, and confirm U0484 does not return.

Approximate repair cost

Repair cost depends on which component actually failed. Typical scenarios for U0484 (parts and labor, USD, independent shop rates): Remove interfering aftermarket device: $0–$150; Repair CAN wiring or connectors: $100–$400; Replace the faulty control module: $300–$1,500. Overall, fixing U0484 usually costs between $0 and $1,500. An accurate diagnosis before buying parts saves money — the most expensive scenario is rarely the first one to check.

Common questions

What is the most common cause of U0484?

The most common causes are: damaged CAN bus wiring or short to power/ground, a faulty module pulling the bus down, water ingress in harness junctions.

How do I diagnose U0484 myself?

Start with a scan: confirm U0484, save the freeze frame and note any companion codes. Then inspect the wiring and connectors related to the vehicle network (CAN bus) communication, and verify the suspect component against live data before buying parts.

Is it safe to drive with U0484?

Depends on what is affected. A single dead convenience module is fine to drive with; loss of communication with engine, braking or steering modules is not. If multiple critical systems drop out, do not drive.

What does OBD2 code U0484 mean?

Will U0484 clear itself?

Sometimes U0484 clears after a few drive cycles if the fault was intermittent — for example a loose connector or a tank of bad fuel. The underlying cause usually remains, so the code tends to return. Clear it once; if it comes back, diagnose rather than erase it repeatedly.

What does U0484 mean?

When U0484 appears on a scan, it means the control module has flagged a problem in the vehicle network (CAN bus) communication: invalid data received from lighting control module rear "A". The fault sits in the vehicle network group of the OBD2 standard.

To set U0484, the control module compares live readings of the vehicle network (CAN bus) communication against calibrated limits, usually over several drive cycles. Alongside the code it stores a freeze frame — a snapshot of rpm, load, coolant temperature and vehicle speed at the moment of failure. Reading that snapshot first saves diagnostic time.

Common symptoms of U0484

no-start or intermittent starting in some cases
random, hard-to-reproduce electrical glitches
intermittent loss of functions (gauges, windows, steering assist)
modules intermittently not communicating with the scanner
multiple warning lights on at once

What causes U0484?

poor grounds or low battery voltage
a faulty module pulling the bus down
water ingress in harness junctions
aftermarket equipment interfering with the bus

How to diagnose U0484

Connect an OBD2 scanner, confirm U0484 is stored, and save the freeze frame data — it shows engine conditions when the fault was detected.
Related codes often reveal the real root cause. Also check manufacturer technical service bulletins (TSB) for your make and model — many U0xxx issues have factory fixes or software updates. Search by VIN on the manufacturer site or nhtsa.gov.
Visually inspect the wiring harness and connectors related to the vehicle network (CAN bus) communication for damage, corrosion, chafing or poor contact.
Measure resistance between CAN-High and CAN-Low at the OBD port with power off — about 60 Ω is healthy.
Scan all modules: the one that does not respond is either the culprit or downstream of the break.
Clear the code, complete a full drive cycle including the conditions from the freeze frame, and confirm U0484 does not return.

How to fix U0484

Start with the cheapest and most common causes before replacing expensive parts:

Remove interfering aftermarket device — $0–$150
Repair CAN wiring or connectors — $100–$400
Replace the faulty control module — $300–$1,500

How much does it cost to fix U0484?

Repair cost depends on which component actually failed. Typical scenarios for U0484 (parts and labor, USD, independent shop rates):

Remove interfering aftermarket device: $0–$150
Repair CAN wiring or connectors: $100–$400
Replace the faulty control module: $300–$1,500

Overall, fixing U0484 usually costs between $0 and $1,500. An accurate diagnosis before buying parts saves money — the most expensive scenario is rarely the first one to check.