AutoCodes – Generic – U1204

U1204 Code - IMA-CAN Malfunction

Quick Answer

The Integrated Motor Assist (IMA) - Controller Area Network (CAN) uses two signal lines, IMACANH and IMACANL, and it receives and transmits multiple signals simultaneously to/from multiple control modules. Common causes include Faulty Powertrain Control Module (PCM), Powertrain Control Module harness is open or shorted, Powertrain Control 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: U1204 indicates IMA-CAN Malfunction.
Common causes: Common causes include Faulty Powertrain Control Module (PCM), Powertrain Control Module harness is open or shorted, Powertrain Control 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 8,054

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 Jul 21, 2020

Description
Possible Causes
How To Fix
Cost to Diagnose
FAQs
Comments
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Code U1204 Description

The Integrated Motor Assist (IMA) - Controller Area Network (CAN) uses two signal lines, IMACANH and IMACANL, and it receives and transmits multiple signals simultaneously to/from multiple control modules.
When the information is not sent from the Powertrain Control Module (PCM) through the IMA-CAN and this condition continues for a specified time or when the information sent from the PCM is abnormal and this condition continues for a specified cycle, the Battery Condition Monitor (BCM) module detects a malfunction and when BUS-OFF is not detected after the time to detect BUS-OFF has passed, a DTC is stored.

OBDII Code U1204 - IMA-CAN Malfunction - AutoCodes.com — U1204 Code - IMA-CAN Malfunction

What does this mean?

What are the Possible Causes of the DTC U1204?

Faulty Powertrain Control Module (PCM)
Powertrain Control Module harness is open or shorted
Powertrain Control Module circuit poor electrical connection
Faulty Battery Condition Monitor (BCM) Module)
Faulty Motor Control Module (MCM)

How to Fix the DTC U1204?

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 U1204 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 U1204 code?

Need more information on how to fix the U1204 code? Get Access to Factory Service Manuals

Need Help with the Code?

Get the U1204 code diagnosed by a professional: Find a repair shop in your area

Information for Specific Makes

U1204 Acura — IMA-CAN Malfunction
U1204 Honda — IMA-CAN Malfunction

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 U1204 Code

What does the OBDII code U1204 indicate?

The U1204 code refers to an IMA-CAN Malfunction, meaning there is a communication issue between the Integrated Motor Assist (IMA) system and the Controller Area Network (CAN) bus.

What are the common symptoms of the U1204 code?

Symptoms may include warning lights on the dashboard (e.g., the check engine light), reduced hybrid system performance, or the IMA system not functioning properly.

What causes the U1204 code to appear?

The code can be triggered by faulty wiring or connections, a malfunctioning IMA control unit, CAN bus communication errors, or issues with related sensors or modules.

Can the U1204 code affect fuel efficiency?

Yes, since the IMA system is integral to hybrid vehicle performance, this code can lead to reduced fuel efficiency if the system is not functioning correctly.

How do you diagnose the U1204 code?

Diagnosing involves scanning for additional codes, inspecting wiring and connectors in the IMA and CAN systems, and testing the communication between modules with specialized diagnostic tools.

Can a weak or failing battery cause the U1204 code?

Yes, low voltage or a failing hybrid battery can disrupt communication within the IMA and CAN systems, potentially triggering this code.

What is the role of the CAN bus related to the U1204 code?

The CAN bus is a communication network that allows various vehicle systems to share data. A malfunction in this network can prevent the IMA system from receiving or transmitting critical information.

How do you fix the U1204 code?

Repairs may include fixing damaged wiring, reconnecting loose connectors, replacing a faulty IMA control unit, or addressing other communication issues within the CAN bus system.

Is it safe to drive with the U1204 code?

While the vehicle may still be drivable, performance issues or reduced efficiency may arise. Prolonged driving without addressing the problem could lead to further damage.

Do you need a professional to fix the U1204 code?

While basic checks like inspecting wiring can be done by a DIYer, diagnosing and repairing CAN bus or IMA system issues often requires specialized tools and expertise, so professional assistance is recommended.