Skip to content
Language: EN
Download

U0073: Control module communication bus A off

A control unit can no longer use data bus A, as if the network were down. Usually a short in the wiring, a connector or a faulty module.

Code U0073 at a glance
CodeU0073
SystemCommunication network
GroupU00xx, Communication buses
TypeGeneric: it means the same on every make
Can you keep driving?With care

What U0073 means

The car’s control units communicate over data networks called buses. This code means bus A has gone out of service for the unit that stored it: it cannot send or receive messages. Which bus is A (normally a CAN bus) is set by each manufacturer.

Most common causes

  • Weak battery or loose terminals
  • Bus wires shorted together, to earth or to a live feed
  • A control unit connector wet, corroded or with bent pins
  • A faulty module shorting the network
  • Aftermarket accessory interfering with the bus

Symptoms

  • Several warning lights on at once
  • Several lost communication codes
  • Car may not start or may go into limp mode
  • Instrument cluster readings not working

Can you drive with U0073?

With care If the car works normally, you can drive carefully to a garage. If brakes, steering or gearbox misbehave, or many warning lights come on, do not drive and call for assistance.

How to check it

Check the battery and its terminals before anything else. Note every U code that appears: the module missing from the scan, or the one with the most faults, is usually close to the problem.

How to read and clear U0073 with Final OBD

Plug an OBD2 scanner in under the steering wheel, switch the ignition on and open Final OBD. Under Faults you’ll see U0073 with this same explanation and whether it’s confirmed, pending or permanent.

With Free you read this code with its short description for nothing, and clear it if the engine stores it over standard OBD. With Pro you get the full explanation, how the car was running when it was logged (revs, temperature, load) and clearing in every control unit.

Clearing the code only turns the light off: if the cause is still there, it comes back. Clear it once it’s fixed, and not right before the ITV. It’s all in how to read and clear fault codes and in the ITV and OBD.

Similar codes

U0073 is a generic code, so it means the same on any make, for example on Alfa Romeo, Cupra, Dacia, Jeep, Nissan, Škoda. See what Final OBD does on your car in makes and models.

What does code U0073 mean?

The car’s control units communicate over data networks called buses. This code means bus A has gone out of service for the unit that stored it: it cannot send or receive messages. Which bus is A (normally a CAN bus) is set by each manufacturer.

Can you drive with U0073?

If the car works normally, you can drive carefully to a garage. If brakes, steering or gearbox misbehave, or many warning lights come on, do not drive and call for assistance.

How do you clear U0073?

With an OBD2 scanner and an app like Final OBD, which clears it for free if it’s stored by the engine control unit. But clearing it only turns the light off: if the cause isn’t fixed, U0073 comes back.