CAN network

U0220 — Lost communication with a module on the CAN network (U0220)

Severity: medium Drive with care, to a shop

What U0220 means

One control unit stopped receiving messages from another module over the CAN bus. Modules constantly exchange data, and when one goes silent the unit stores U0220. The exact definition varies by manufacturer: some sources tie this code to the power steering module, but in the standard SAE list that module is U0131. Confirm the definition for your make with a scan tool.

Symptoms

  • Heavy steering or loss of power assist
  • Power steering warning light
  • Several warning lights at once
  • Function of the affected module unavailable
  • Code returns after clearing

Possible causes

  1. Open, shorted or chafed CAN bus wiring
  2. Corroded connectors or terminals
  3. Blown fuse feeding the module
  4. Poor ground or missing power at the module
  5. Faulty module loading the bus
  6. Failure of the power steering module itself (if the code applies to it)
  7. Low battery voltage

How to diagnose

  1. Run a full-module scan and map which modules are not responding.
  2. Look up the U0220 definition for the specific make and model.
  3. Test the battery and system voltage.
  4. Check fuses and relays that power the affected module.
  5. Inspect the harness and connectors for chafing, moisture and corrosion.
  6. Check power and ground at the module connector with a multimeter.
  7. Measure CAN bus resistance (about 60 ohms between CAN-H and CAN-L) and voltages at the diagnostic connector.
  8. Unplug suspect modules one at a time, only following a documented procedure.

Common fixes

  • Repair or replace the damaged wiring section
  • Clean or replace corroded connectors and terminals
  • Replace the fuse after finding the cause of the overload
  • Restore the ground or power supply to the module
  • Replace or reprogram the faulty module

Questions and answers

What does U0220 mean?

It is a lost-communication code for a module on the CAN network. The exact name depends on the manufacturer, so confirm it with a scan tool for your make.

Can I drive with U0220?

If the steering is heavy or several warning lights are on, drive carefully to a shop. With minor symptoms you can drive, but get it diagnosed soon.

Can I just clear the code?

You can, but if the cause is wiring, power or a module, it will come back. Find the fault first.

This is general information about the code. The meaning can differ between makes and models: a scan tool and the repair manual for your car will show the exact cause.