U0015 — Medium Speed CAN Communication Bus (-) Open

What does OBD2 code U0015 mean?

OBD2 code U0015 flags a problem with the vehicle network (CAN bus) communication (medium speed CAN communication bus (-) open). Short, gentle driving to a shop is usually possible. Common culprits: poor grounds or low battery voltage, corroded connectors, especially in wet areas, water ingress in harness junctions.

Will U0015 clear itself?

Sometimes U0015 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.

Is it safe to drive with U0015?

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 much does it cost to fix U0015?

Remove interfering aftermarket device — $0–$150; Repair CAN wiring or connectors — $100–$400; Replace the faulty control module — $300–$1,500. Exact cost depends on the root cause, your vehicle and local labor rates — a proper diagnosis is the cheapest first step.

What is the most common cause of U0015?

The most common causes are: poor grounds or low battery voltage, corroded connectors, especially in wet areas, water ingress in harness junctions.

What does U0015 mean?

Seeing U0015 on your scanner? The control unit has caught the vehicle network (CAN bus) communication operating outside its calibrated window. The formal description is “Medium Speed CAN Communication Bus (-) Open”, and the code is grouped under vehicle network faults.

To set U0015, 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 U0015

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

What causes U0015?

• poor grounds or low battery voltage
• damaged CAN bus wiring or short to power/ground
• aftermarket equipment interfering with the bus
• corroded connectors, especially in wet areas

How to diagnose U0015

1. Connect an OBD2 scanner, confirm U0015 is stored, and save the freeze frame data — it shows engine conditions when the fault was detected.
2. 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.
3. Visually inspect the wiring harness and connectors related to the vehicle network (CAN bus) communication for damage, corrosion, chafing or poor contact.
4. Measure resistance between CAN-High and CAN-Low at the OBD port with power off — about 60 Ω is healthy.
5. Scan all modules: the one that does not respond is either the culprit or downstream of the break.
6. Clear the code, complete a full drive cycle including the conditions from the freeze frame, and confirm U0015 does not return.

How to fix U0015

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 U0015?

Repair cost depends on which component actually failed. Typical scenarios for U0015 (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 U0015 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.

Can you drive with U0015?

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.

Related OBD2 codes

• U0001: High Speed CAN Communication Bus
• U0002: High Speed CAN Communication Bus Performance
• U0003: High Speed CAN Communication Bus (+) Open
• U0004: High Speed CAN Communication Bus (+) Low
• U0005: High Speed CAN Communication Bus (+) High
• U0006: High Speed CAN Communication Bus (-) Open