U023B — Lost Communication With Image Processing Module "B"

OBD2 code U023B flags a problem with the vehicle network (CAN bus) communication (lost communication with image processing module "B"). Short, gentle driving to a shop is usually possible. Common culprits: aftermarket equipment interfering with the bus, water ingress in harness junctions, damaged CAN bus wiring or short to power/ground.

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 U023B 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 U023B does not return.

Approximate repair cost

Repair cost depends on which component actually failed. Typical scenarios for U023B (parts and labor, USD, independent shop rates): Repair CAN wiring or connectors: $100–$400; Replace the faulty control module: $300–$1,500; Remove interfering aftermarket device: $0–$150. Overall, fixing U023B 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 U023B?

The most common causes are: aftermarket equipment interfering with the bus, water ingress in harness junctions, damaged CAN bus wiring or short to power/ground.

Is it safe to drive with U023B?

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 do I diagnose U023B myself?

Start with a scan: confirm U023B, 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.

Will U023B clear itself?

Sometimes U023B 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 are the symptoms of U023B?

Drivers most often notice: random, hard-to-reproduce electrical glitches, modules intermittently not communicating with the scanner, multiple warning lights on at once, intermittent loss of functions (gauges, windows, steering assist).

What does U023B mean?

U023B is logged by the onboard diagnostics when the vehicle network (CAN bus) communication does not behave as expected. The official definition is “Lost Communication With Image Processing Module "B"”. This is a vehicle network category code.

To set U023B, 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.

What causes U023B?

corroded connectors, especially in wet areas
damaged CAN bus wiring or short to power/ground
a faulty module pulling the bus down
aftermarket equipment interfering with the bus

Common symptoms of U023B

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

How to diagnose U023B

Connect an OBD2 scanner, confirm U023B 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 U023B does not return.

How to fix U023B

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

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

How much does it cost to fix U023B?

Repair cost depends on which component actually failed. Typical scenarios for U023B (parts and labor, USD, independent shop rates):

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

Overall, fixing U023B 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.