U0191 — Lost Communication With Television

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 U0191 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 U0191 does not return.

Approximate repair cost

Repair cost depends on which component actually failed. Typical scenarios for U0191 (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 U0191 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

Is it safe to drive with U0191?

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 U0191 myself?

Start with a scan: confirm U0191, 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.

What are the symptoms of U0191?

Drivers most often notice: random, hard-to-reproduce electrical glitches, multiple warning lights on at once, no-start or intermittent starting in some cases, modules intermittently not communicating with the scanner.

Will U0191 clear itself?

Sometimes U0191 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 is the most common cause of U0191?

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

What does U0191 mean?

When U0191 appears on a scan, it means the control module has flagged a problem in the vehicle network (CAN bus) communication: lost communication with television. The fault sits in the vehicle network group of the OBD2 standard.

The module monitors this system continuously while driving. When readings fall outside the expected range for a defined number of drive cycles, it stores U0191 and switches on the warning light. Freeze frame data saved with the code shows the exact conditions — rpm, load, temperature, speed — at the moment the fault was detected, which is the best starting point for diagnosis.

What causes U0191?

damaged CAN bus wiring or short to power/ground
poor grounds or low battery voltage
water ingress in harness junctions
corroded connectors, especially in wet areas

Common symptoms of U0191

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

How to diagnose U0191

Connect an OBD2 scanner, confirm U0191 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 U0191 does not return.

How to fix U0191

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 U0191?

Repair cost depends on which component actually failed. Typical scenarios for U0191 (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 U0191 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.