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U0095 — Vehicle Communication Bus H Low

Generic OBD-II · all makesNetwork / communication

Code U0095 indicates that the voltage on the High-speed Controller Area Network (CAN Bus H) is lower than the expected operating range. This suggests a communication failure where the signal on the high line is being pulled toward ground or is interrupted.

Symptoms

What causes it — most likely first

1. CAN-High Wiring Short to Ground

The CAN-High signal wire is physically pinched or rubbed through, creating an electrical path to the vehicle chassis.

2. Broken CAN-High Circuit

An open circuit or break in the wiring prevents the high-voltage signal from reaching the destination module.

3. Corroded Connectors

Moisture or oxidation in a module connector increases resistance or creates a bridge that pulls the signal voltage down.

4. Faulty Network Module

An internal failure within a connected module (such as the BCM or ABS module) is pulling the entire bus voltage low.

5. PCM/ECM Internal Failure

A failure in the main engine computer's communication transceiver, though this is significantly less common than wiring faults.

How it's diagnosed

  1. Perform a visual inspection of the CAN bus wiring harness for chafing, burns, or rodent damage.
  2. Inspect all major module connectors for corrosion, bent pins, or water ingress.
  3. Measure the resistance between the CAN-High line and ground using a digital multimeter; a very low reading indicates a short.
  4. Verify the voltage on the CAN-High line with the ignition on to confirm it is below the manufacturer's specification.
  5. Disconnect network modules one by one to identify if a specific module is causing the bus voltage to drop.

Code facts & related codes

SystemNetwork / communication
StandardizationSAE generic — identical on every make

Frequently asked

Can a weak battery cause a U0095 code?

Low system voltage can cause general communication errors, but U0095 specifically identifies a voltage level issue on the High line, which is more typically related to wiring or hardware failure.

Should I replace the PCM if I see this code?

No; U0095 is rarely caused by the PCM. It is far more common for the issue to be a wiring short or a failed peripheral module. The PCM should only be replaced after all wiring and other modules have been ruled out.

Is it safe to drive with a communication bus error?

It is generally unsafe, as the vehicle may lose critical safety functions such as electronic stability control, ABS, or power steering communication.