High Speed CAN Communication Bus (+) Low
What it means
A module has detected that the (+) wire of the high-speed CAN bus is lower than expected, which usually happens when the wire touches the vehicle body or a ground circuit. Messages then become corrupted or communication between modules stops. The code is usually stored in another module, and several U codes with it confirm the problem is in the bus rather than one module.
Symptoms5
- Several warning lights on the cluster at once.
- Scan tool cannot communicate with several modules or the whole bus.
- Some gauges stop working or the transmission goes into limp mode.
- Hard starting or no start on some vehicles.
- Fault appears when certain parts are moved or in humid weather.
Possible causes5
- The (+) wire shorted to the vehicle body through insulation worn by chafing.
- Water or corrosion inside a connector linking the wire to ground.
- Wire pinched under a seat or panel or pierced by a screw after service or an accessory install.
- A module with an internal fault pulling the wire to ground.
- Harness damage after a collision or from rodents.
How to diagnose5
- Read codes from all modules and note whether communication is lost completely or only with some modules.
- Disconnect the battery and measure resistance between the (+) wire and the vehicle body; a clear path to ground means a short.
- With the battery disconnected, measure resistance between the two bus wires: a healthy bus has two 120-ohm termination resistors and reads about 60 ohms; about 120 ohms points to an open or a missing resistor, and near zero points to the two wires shorted together.
- Disconnect modules one at a time and measure again; if the short disappears after unplugging a module, the problem is that module or its branch.
- Inspect the wiring route in areas prone to chafing and water, such as under the carpet, along body edges and at accessory installs.
How to fix5
- Dry and clean the wet connector, and fix the source of the water leak.
- Repair the damaged insulation or replace the damaged wire section, and secure it away from sharp edges.
- Free the pinched wire or the wire pierced by a screw and repair it.
- Replace the module pulling the wire to ground if proven faulty, then program and code it.
- Clear codes in all modules and confirm communication returns and the code stays off.
Repair cost
In Saudi riyals; the highlighted part is the expected range for this fault.
In the Saudi market: SAR 150–3,000 (≈ USD 40–800)
Our prices come from the Saudi market, converted at a fixed rate (SAR 3.75 per USD). Prices in your country may differ a lot, so we show the cost level.
The cost is low if the short is at a connector or an easy-to-reach spot, rises with the time needed to trace the harness, and is highest if a control module is causing the short.
Prices are rough estimates for common cars at independent workshops and vary with the car and the source of the part.
Prices last updated: September 2026
Frequently asked questions
What is the most common cause of this code?
The wire shorting to the vehicle body through damaged insulation or water in a connector, and sometimes a wire pinched while installing an accessory.
How do I know if a control module is the cause?
Disconnect modules one at a time and measure the wire to ground again. If the short goes away after unplugging a module, that module or its branch is the cause.
Can I drive with this code?
With caution and for a short distance if the engine runs, because the transmission and ABS systems may stop working or run in limp mode.
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