AutoCodes – Mercury – U0115 Mercury

U0115 Mercury Code - Lost Communication With ECM/PCM 'B'

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 Engine Control Module (ECM)/Powertrain Control Module (PCM) 'B', ECM/PCM 'B' harness is open or shorted, ECM/PCM 'B' 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: U0115 Mercury indicates Lost Communication With ECM/PCM 'B'.
Common causes: Common causes include Faulty Engine Control Module (ECM)/Powertrain Control Module (PCM) 'B', ECM/PCM 'B' harness is open or shorted, ECM/PCM 'B' 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 452

How popular is this code, among other codes? Low

Repair Importance Level

Urgent (Diagnose now) (3 / 3)

Repair Difficulty Level

Advanced (Pro) (3 / 3)

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Table of contents Created and updated by William Orellana on Jan 08, 2021

Description
Possible Causes
How To Fix
Cost to Diagnose
FAQs
Comments
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Code U0115 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 Engine Control Module (ECM)/Powertrain Control Module (PCM) 'B' has not been received.

OBDII Code U0115 Mercury - Lost Communication With ECM/PCM 'B' - AutoCodes.com — U0115 Mercury Code - Lost Communication With ECM/PCM 'B'

What does this mean?

What are the Possible Causes of the DTC U0115 Mercury?

Faulty Engine Control Module (ECM)/Powertrain Control Module (PCM) 'B'
ECM/PCM 'B' harness is open or shorted
ECM/PCM 'B' circuit poor electrical connection

How to Fix the DTC U0115 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 U0115 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.

Need more information about the U0115 Mercury code?

Need more information on how to fix the U0115 Mercury code? Get Access to Factory Service Manuals

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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 U0115 Mercury Code

1. What does the OBDII code U0115 for Mercury mean?

The code U0115 indicates a communication problem between the vehicle's control module and the ECM/PCM 'B'.

2. What are the common symptoms of U0115 in a Mercury vehicle?

Common symptoms include engine stalling, rough idling, poor fuel efficiency, and issues with transmission shifting.

3. What are the possible causes of the U0115 code in a Mercury vehicle?

Possible causes include a faulty ECM/PCM 'B', damaged wiring or connectors, software issues, or a weak battery.

4. How can I diagnose the U0115 code in my Mercury?

Diagnosis typically involves checking the wiring and connectors for damage, ensuring the battery is in good condition, and using a diagnostic scanner to communicate with the ECM/PCM 'B'.

5. Can I still drive my Mercury with the U0115 code present?

It is not recommended to drive the vehicle with the U0115 code active, as it can lead to further damage and safety hazards.

6. How can I repair the U0115 code in my Mercury?

Repair options include fixing any damaged wiring or connectors, replacing the ECM/PCM 'B' if necessary, and clearing the code with a diagnostic scanner.

7. Will disconnecting the battery reset the U0115 code in my Mercury?

Disconnecting the battery may temporarily clear the code, but it is not a permanent solution. It is essential to diagnose and repair the underlying issue to prevent the code from reoccurring.

8. Can a DIY enthusiast fix the U0115 code in a Mercury, or should it be done by a professional?

While some basic checks like inspecting wiring can be done by a DIY enthusiast, diagnosing and repairing the U0115 code may require professional assistance due to the complexity of the vehicle's control systems.

9. How much does it typically cost to repair the U0115 code in a Mercury?

The cost of repair can vary depending on the underlying issue, the labor rates in your area, and whether new parts are needed. It is advisable to obtain quotes from reputable mechanics or dealerships.

10. Is the U0115 code specific to Mercury vehicles, or can it occur in other car makes and models?

The U0115 code can occur in various car makes and models, as it indicates a generic communication problem between the control module and the ECM/PCM 'B'.