AutoCodes – Mercury – U0231 Mercury

U0231 Mercury Code - Lost Communication With Rain Sensing Module

Quick Answer

A Controller Area Network (CAN) is a vehicle bus standard designed to interconnect automotive devices without a host computer. Common causes include Faulty Rain Sensing Module, Rain Sensing Module harness is open or shorted, Rain Sensing Module circuit poor electrical connection. Severity is High - diagnose this code as soon as possible. Driving is not recommended if the warning light is flashing, the engine runs poorly, or safety-related symptoms are present.

What it means: U0231 Mercury indicates Lost Communication With Rain Sensing Module.
Common causes: Common causes include Faulty Rain Sensing Module, Rain Sensing Module harness is open or shorted, Rain Sensing Module circuit poor electrical connection.
Severity: High - diagnose this code as soon as possible.
Can I drive?: Driving is not recommended if the warning light is flashing, the engine runs poorly, or safety-related symptoms are present.

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Code Popularity 768

How popular is this code, among other codes? Low

Repair Importance Level

Urgent (Diagnose now) (3 / 3)

Repair Difficulty Level

Advanced (Pro) (3 / 3)

What is this?

Table of contents Created and updated by William Orellana on Apr 04, 2020

Description
Possible Causes
How To Fix
Cost to Diagnose
FAQs
Comments
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Code U0231 Mercury Description

A Controller Area Network (CAN) is a vehicle bus standard designed to interconnect automotive devices without a host computer. Operating information and commands are exchanged among the devices. The devices have programmed information about what messages are needed to be exchanged on the serial data circuits. CAN bus uses two dedicated wires for communication. The wires are called CAN high and CAN low. When the CAN bus is in idle mode, both lines carry 2.5V. When data bits are being transmitted, the CAN high line goes to 3.75V, and the CAN low drops to 1.25V, thereby generating a 2.5V differential between the lines. Since communication relies on a voltage differential between the two bus lines, the CAN bus is NOT sensitive to inductive spikes, electrical fields, or other noise. The Diagnostic Trouble Code (DTC) sets when a periodic message from the has not been received.

OBDII Code U0231 Mercury - Lost Communication With Rain Sensing Module - AutoCodes.com — U0231 Mercury Code - Lost Communication With Rain Sensing Module

What does this mean?

What are the Possible Causes of the DTC U0231 Mercury?

Faulty Rain Sensing Module
Rain Sensing Module harness is open or shorted
Rain Sensing Module circuit poor electrical connection

How to Fix the DTC U0231 Mercury?

Review the 'Possible Causes' above and visually examine the corresponding wiring harness and connectors. Check for damaged components and inspect connector pins for signs of being broken, bent, pushed out, or corroded.

What is the Cost to Diagnose the Code?

Labor: 1.0

To diagnose the U0231 Mercury code, it typically requires 1.0 hour of labor. Rates vary by location, vehicle, and shop. Many shops charge between $80–$150 per hour; dealerships and metro areas may be higher, independents may be lower.

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About the author: William Orellana is a Master Mechanic and Mechanical Engineer with over 30 years of experience diagnosing and repairing vehicles. Learn more about his background.

Frequently Asked Questions about U0231 Mercury Code

What does the OBDII code U0231 mean?

The OBDII code U0231 indicates that there is a lost communication with the rain sensing module, suggesting that the vehicle's computer is unable to receive data from this component.

What are the common symptoms of code U0231?

Common symptoms include malfunctioning windshield wipers, erratic wiper operation, or wipers that do not respond to rain conditions as intended.

What could cause the U0231 code to trigger?

Causes may include a faulty rain sensing module, damaged wiring or connectors, or issues with the vehicle's main control module that affect communication.

How can I diagnose the U0231 code?

To diagnose the U0231 code, check for other related trouble codes, inspect the wiring and connectors for damage, and test the functionality of the rain sensing module.

What should I do if I find a wiring issue when diagnosing U0231?

If you find damaged wiring or connectors, repair or replace them as necessary to restore proper communication between the rain sensing module and the vehicle's computer.

Is it safe to drive a vehicle with the U0231 code?

While the vehicle may still be operable, it is advisable to address the U0231 code as it can affect the functionality of the windshield wipers, which is critical for visibility in rain.

What tools do I need to troubleshoot the U0231 code?

You will need an OBDII scanner to read codes, a multimeter to check wiring and voltage, and possibly a repair manual specific to your vehicle for wiring diagrams.

Can I fix the U0231 code myself?

If you have automotive repair experience, you can attempt to fix the U0231 code by checking wiring and connectors. However, if the rain sensing module is malfunctioning, it may need replacement, which could require professional assistance.

How much does it typically cost to repair the U0231 code?

Repair costs can vary widely depending on the issue; if itâ€™s a simple wiring fix, it may be inexpensive, while replacing the rain sensing module could cost anywhere from $100 to $500 or more, depending on labor and parts.

Will clearing the U0231 code fix the problem?

Clearing the code may temporarily remove the warning light, but if the underlying issue (such as a faulty module or wiring problem) is not addressed, the code is likely to reappear.