AutoCodes – Generic – U0240

U0240 Code - Lost Communication With Entrapment Control Module '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 Entrapment Control Module 'B', Entrapment Control Module 'B' harness is open or shorted, Entrapment Control Module '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: U0240 indicates Lost Communication With Entrapment Control Module 'B'.
Common causes: Common causes include Faulty Entrapment Control Module 'B', Entrapment Control Module 'B' harness is open or shorted, Entrapment Control Module '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 2,482

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 U0240 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 Entrapment Control Module 'B' has not been received.

OBDII Code U0240 - Lost Communication With Entrapment Control Module 'B' - AutoCodes.com — U0240 Code - Lost Communication With Entrapment Control Module 'B'

What does this mean?

What are the Possible Causes of the DTC U0240?

Faulty Entrapment Control Module 'B'
Entrapment Control Module 'B' harness is open or shorted
Entrapment Control Module 'B' circuit poor electrical connection

How to Fix the DTC U0240?

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 U0240 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 U0240 Code

1. What are common symptoms of OBDII code U0240?

The common symptoms of OBDII code U0240 include the malfunction indicator light (MIL) being illuminated on the dashboard, difficulty shifting gears, and issues with the transmission control system.

2. What does the OBDII code U0240 indicate?

OBDII code U0240 indicates a communication problem between the vehicle's onboard diagnostic system and the Entrapment Control Module 'B', which is typically related to the transmission control system.

3. What are possible causes of OBDII code U0240?

Possible causes of OBDII code U0240 include a faulty Entrapment Control Module 'B', damaged wiring or connectors in the communication network, software issues, or a poor electrical connection.

4. How can I diagnose OBDII code U0240?

Diagnosing OBDII code U0240 involves using a diagnostic scan tool to retrieve the code, checking the wiring and connectors for any visible damage, and testing the communication between the modules using a multimeter or oscilloscope.

5. Can OBDII code U0240 be fixed by resetting the vehicle's computer?

While resetting the vehicle's computer may temporarily clear the code, it is not a permanent solution for OBDII code U0240. It is important to diagnose the underlying issue causing the communication problem and address it accordingly.

6. What are some repair tips for OBDII code U0240?

Repair tips for OBDII code U0240 include checking and repairing any damaged wiring or connectors, ensuring a secure electrical connection, updating software if necessary, and replacing the Entrapment Control Module 'B' if it is found to be faulty.

7. Is it safe to continue driving with OBDII code U0240 present?

It is not recommended to continue driving with OBDII code U0240 present, as it can lead to further transmission issues and potentially unsafe driving conditions. It is best to address the problem promptly to prevent any potential damage.

8. Can a DIY enthusiast fix OBDII code U0240 at home?

While some aspects of diagnosing and repairing OBDII code U0240 can be done by a DIY enthusiast, it is recommended to consult a professional mechanic for a thorough diagnosis and proper repair to ensure the issue is resolved correctly.

9. How much does it cost to fix OBDII code U0240?

The cost to fix OBDII code U0240 can vary depending on the underlying cause of the issue, the extent of the repair needed, and labor rates in your area. It is best to obtain a diagnosis from a mechanic to get an accurate estimate.

10. Can OBDII code U0240 be prevented in the future?

While some causes of OBDII code U0240 may be preventable through regular maintenance and inspections, others may be due to factors beyond control. Keeping up with routine vehicle checks and addressing any communication issues promptly can help prevent the code from reoccurring.