U0007 — High Speed CAN Communication Bus (-) Low

How do I diagnose U0007 myself?

Start with a scan: confirm U0007, 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 U0007?

Drivers most often notice: intermittent loss of functions (gauges, windows, steering assist), multiple warning lights on at once, no-start or intermittent starting in some cases, modules intermittently not communicating with the scanner.

Will U0007 clear itself?

Sometimes U0007 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 OBD2 code U0007 mean?

U0007 — High Speed CAN Communication Bus (-) Low. A fault in the vehicle network (CAN bus) communication. Short, gentle driving to a shop is usually possible. Typical causes: a faulty module pulling the bus down, water ingress in harness junctions, poor grounds or low battery voltage.

What is the most common cause of U0007?

The most common causes are: a faulty module pulling the bus down, water ingress in harness junctions, poor grounds or low battery voltage.

What does U0007 mean?

The engine control module sets U0007 when it detects a fault in the vehicle network (CAN bus) communication. In practical terms: high speed CAN communication bus (-) low. The code belongs to the vehicle network group of OBD2 codes.

This code does not appear from a single bad reading: the module must see the fault condition repeat under defined operating conditions before it turns on the warning light. The freeze frame captured with U0007 — engine load, rpm, temperature, speed — tells you exactly when the problem occurs, so reproduce those conditions when testing.

Common symptoms of U0007

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

What causes U0007?

• poor grounds or low battery voltage
• damaged CAN bus wiring or short to power/ground
• aftermarket equipment interfering with the bus
• a faulty module pulling the bus down
• corroded connectors, especially in wet areas
• water ingress in harness junctions

How to diagnose U0007

1. Connect an OBD2 scanner, confirm U0007 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 U0007 does not return.

How to fix U0007

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

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

How much does it cost to fix U0007?

Repair cost depends on which component actually failed. Typical scenarios for U0007 (parts and labor, USD, independent shop rates):

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

Overall, fixing U0007 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 U0007?

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