U0231: Lost Communication With Rain Sensing Module

What it means

A control module has stopped receiving expected messages from the rain sensing module. The code identifies the communication loss; automatic wiper or lighting behavior may be affected if equipped.

How it works

The rain sensing module detects moisture at the windshield and reports it so the vehicle can control automatic wipers or related functions, if equipped. U0231 sets when a module stops receiving the expected messages from the rain sensing module; it does not mean the wiper motor itself has failed.

Common causes

Most likely first.

1. Loss of power or ground to the module
2. Open, shorted, or damaged network wiring or connector
3. Failed rain sensing module

Symptoms

• Automatic rain-sensing wiper operation may be unavailable
• A communication fault may be stored; a warning may appear depending on the vehicle

How to diagnose it

1. Scan all modules for communication codes and freeze-frame details, checking whether the fault is isolated to the rain sensing module.
2. Test the wipers using their manual settings and confirm whether only automatic rain-sensing operation is affected.
3. Inspect the rain sensor's windshield mounting area, connector, and nearby wiring for a loose fit, water entry, or damage.
4. Check the module's power and ground against the manufacturer's specification.
5. Test the network wiring between the rain sensing module and vehicle network for opens, shorts, or poor connections.
6. If its supply and network circuits are sound, verify module communication with a capable scan tool before replacing the sensor module.

Common fixes

• Reconnect or clean a loose or corroded rain sensing module connector.
• Repair damaged wiring or network connections at the sensor.
• Correct a loose sensor mounting or connection at the windshield if inspection identifies it.
• Replace the rain sensing module if its power, ground, and network circuits test correctly but it remains offline.

Can I keep driving?

You can usually drive if the wipers work on manual settings, but do not rely on automatic wiping in rain. Use manual wiper control and avoid driving when visibility cannot be maintained.