AutoCodes – Generic – U011B

U011B Code - Lost Communication With Rocker Arm Control Module 'A'

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 Rocker Arm Control Module 'A', Rocker Arm Control Module 'A' harness is open or shorted, Rocker Arm Control Module 'A' 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: U011B indicates Lost Communication With Rocker Arm Control Module 'A'.
Common causes: Common causes include Faulty Rocker Arm Control Module 'A', Rocker Arm Control Module 'A' harness is open or shorted, Rocker Arm Control Module 'A' 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 23,593

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 Mar 30, 2020

Description
Possible Causes
How To Fix
Cost to Diagnose
FAQs
Comments
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Code U011B 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 Rocker Arm Control Module 'A' has not been received.

OBDII Code U011B - Lost Communication With Rocker Arm Control Module 'A' - AutoCodes.com — U011B Code - Lost Communication With Rocker Arm Control Module 'A'

What does this mean?

What are the Possible Causes of the DTC U011B?

Faulty Rocker Arm Control Module 'A'
Rocker Arm Control Module 'A' harness is open or shorted
Rocker Arm Control Module 'A' circuit poor electrical connection

How to Fix the DTC U011B?

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 U011B 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 U011B Code

1. What are the common symptoms of OBDII code U011B - Lost Communication With Rocker Arm Control Module 'A'?

- Common symptoms include rough idling, engine misfires, poor acceleration, and potentially an illuminated check engine light.

2. What are some possible causes of OBDII code U011B?

- Possible causes include a faulty rocker arm control module, damaged wiring or connectors, a communication network issue, or a malfunctioning powertrain control module (PCM).

3. How can I diagnose the cause of OBDII code U011B?

- Diagnosis typically involves checking the rocker arm control module for faults, inspecting the wiring and connectors for damage, and using a diagnostic scanner to assess communication between modules.

4. Can I still drive my vehicle with OBDII code U011B present?

- It is not recommended to drive your vehicle with this code present, as it can lead to engine performance issues and potential further damage if left unaddressed.

5. How can I repair OBDII code U011B?

- Repair usually involves addressing the root cause of the communication issue, which may include replacing the rocker arm control module, repairing damaged wiring, or reprogramming the PCM.

6. Is it possible to reset OBDII code U011B without fixing the underlying issue?

- While clearing the diagnostic trouble codes can temporarily remove the warning light, the issue causing the code will persist until properly addressed.

7. Are there any specific vehicles known to commonly experience OBDII code U011B?

- This code can be found in various vehicles equipped with a rocker arm control module, particularly in newer models with advanced engine control systems.

8. Can a DIY enthusiast fix OBDII code U011B at home?

- Depending on the specific cause, some DIY enthusiasts with the necessary tools and knowledge may be able to address this code at home. However, complex issues may require professional assistance.

9. How much can I expect to pay for repairs related to OBDII code U011B?

- Repair costs can vary widely based on the underlying cause and the labor rates of the repair shop. It's advisable to obtain estimates from different mechanics or dealerships.

10. What steps can I take to prevent OBDII code U011B from occurring in the future?

- Regular maintenance, such as checking and cleaning electrical connections, inspecting wiring harnesses for damage, and addressing warning lights promptly, can help prevent this code from reoccurring.