AutoCodes – Buick – U1255 Buick

U1255 Buick Code - Lost Communications

Quick Answer

Modules connected to the class 2 serial data circuit monitor for serial data communications during normal vehicle operation. Common causes include Loose control module connectors, Faulty control module, Control modules poor lectrical 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: U1255 Buick indicates Lost Communications.
Common causes: Common causes include Loose control module connectors, Faulty control module, Control modules poor lectrical 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 9,830

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 May 05, 2020

Description
Possible Causes
How To Fix
Tech Notes
Cost to Diagnose
FAQs
Comments
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Code U1255 Buick Description

Modules connected to the class 2 serial data circuit monitor for serial data communications during normal vehicle operation. Operating information and commands are exchanged among the modules. When a module receives a message for a critical operating parameter, the module records the identification number of the module which sent the message. These node alive messages are used for State of Health monitoring. A critical operating parameter is one which, when not received, requires that the module use a default value for that parameter. When a module does not associate an identification number with at least one critical parameter within 5 seconds of beginning serial data communication, DTC U1000 or U1255 is set. When more than one critical parameter does not have an identification number associated with it, the DTC will only be reported once. The following modules communicate on the class 2 serial data circuit:
- Audio amplifier
- Cellular telephone module w/UV8
- Dash integration module (DIM)
- Digital radio receiver
- Driver door module (DDM)
- Driver door switch assembly (DDSA)
- Electronic brake control module (EBCM)
- Electronic suspension control module (ESC)
- Front passenger door module (FPDM)
- Inflatable restraint sensing and diagnostic module (SDM)

OBDII Code U1255 Buick - Lost Communications - AutoCodes.com — U1255 Buick Code - Lost Communications

What does this mean?

What are the Possible Causes of the DTC U1255 Buick?

Loose control module connectors
Faulty control module
Control modules poor lectrical connection
Control Modules harness open or shorted

How to Fix the DTC U1255 Buick?

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 does this mean?

Code Tech Notes

The code is set when the Powertrain Control Module (PCM) does not receive a message that it was expecting from another control module (e.g. Transmission Control Module, ABS Module), and does not know which control module did not send the message.

As with all loss of communication concerns, inspect the power, ground, and serial data circuits to the suspect module prior to replacing any parts.

What is the Cost to Diagnose the Code?

Labor: 1.0

To diagnose the U1255 Buick 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 U1255 Buick Code

1. What does the OBDII code U1255 mean on a Buick?

U1255 indicates a "Lost Communications" issue, meaning a control module, such as the PCM or BCM, is unable to communicate with other modules over the vehicle's data network.

2. What are common symptoms of code U1255 on a Buick?

Symptoms may include a check engine light, malfunctioning gauges, failure of certain electronic systems, or intermittent issues with features like power windows or the radio.

3. What causes the U1255 code to appear on a Buick?

Common causes include damaged wiring, faulty connectors, a failed control module, or issues with the vehicle's communication bus (usually the CAN bus).

4. Can a weak battery cause the U1255 code on a Buick?

Yes, a weak or failing battery can cause voltage drops that disrupt communication between modules, potentially triggering the U1255 code.

5. How do you diagnose the U1255 code on a Buick?

Diagnosis involves scanning for additional codes, inspecting wiring and connectors for damage or corrosion, and testing the voltage and ground at the affected module.

6. Can a faulty module trigger the U1255 code on a Buick?

Yes, if a module like the PCM or BCM fails, it can stop communicating with other modules, leading to the U1255 code.

7. Is it safe to drive a Buick with the U1255 code?

It depends on the severity of the issue. While some minor communication errors may not affect drivability, more serious faults could lead to safety concerns or system malfunctions.

8. How is the U1255 code fixed on a Buick?

Repairs may include replacing damaged wiring, cleaning or replacing corroded connectors, or reprogramming or replacing a faulty module.

9. Can clearing the U1255 code fix the issue on a Buick?

Clearing the code may temporarily turn off the check engine light, but if the underlying issue isnâ€™t resolved, the code will likely return.

10. What tools are needed to troubleshoot the U1255 code on a Buick?

A diagnostic scanner capable of reading manufacturer-specific codes, a multimeter for testing electrical circuits, and possibly a CAN bus diagnostic tool are typically needed.