AutoCodes – Generic – U0684

U0684 Code - Lost Communication With Catalyst Temperature Bank 1 Sensor 1

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 Catalyst Temperature Bank 1 Sensor 1, Catalyst Temperature Bank 1 Sensor 1 harness is open or shorted, Catalyst Temperature Bank 1 Sensor 1 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: U0684 indicates Lost Communication With Catalyst Temperature Bank 1 Sensor 1.
Common causes: Common causes include Faulty Catalyst Temperature Bank 1 Sensor 1, Catalyst Temperature Bank 1 Sensor 1 harness is open or shorted, Catalyst Temperature Bank 1 Sensor 1 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 1,183

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 14, 2020

Description
Possible Causes
How To Fix
Cost to Diagnose
FAQs
Comments
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Code U0684 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 Catalyst Temperature Bank 1 Sensor 1 has not been received.

OBDII Code U0684 - Lost Communication With Catalyst Temperature Bank 1 Sensor 1 - AutoCodes.com — U0684 Code - Lost Communication With Catalyst Temperature Bank 1 Sensor 1

What does this mean?

What are the Possible Causes of the DTC U0684?

Faulty Catalyst Temperature Bank 1 Sensor 1
Catalyst Temperature Bank 1 Sensor 1 harness is open or shorted
Catalyst Temperature Bank 1 Sensor 1 circuit poor electrical connection

How to Fix the DTC U0684?

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 U0684 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 U0684 code?

Need more information on how to fix the U0684 code? Get Access to Factory Service Manuals

Need Help with the Code?

Get the U0684 code diagnosed by a professional: Find a repair shop in your area

Information for Specific Makes

U0684 Chrysler — Lost Communication With Catalyst Temperature Bank 1 Sensor 1
U0684 Dodge — Lost Communication With Catalyst Temperature Bank 1 Sensor 1
U0684 Jeep — Lost Communication With Catalyst Temperature Bank 1 Sensor 1
U0684 RAM — Lost Communication With Catalyst Temperature Bank 1 Sensor 1

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 U0684 Code

1. What are the common symptoms of OBDII code U0684?

- Common symptoms include the Check Engine light coming on, poor engine performance, and potential issues with fuel efficiency.

2. What can cause the OBDII code U0684 to appear?

- The code U0684 may appear due to a faulty catalyst temperature sensor, wiring issues, or a poor connection between the sensor and the vehicle's ECM.

3. How can I diagnose the cause of OBDII code U0684?

- Diagnosing the code usually involves checking the connections of the catalyst temperature sensor, inspecting the wiring for any damage, and testing the sensor itself for proper functionality.

4. Can a bad catalytic converter trigger the U0684 code?

- While a faulty catalytic converter may not directly trigger the U0684 code, it can indirectly affect the sensor's performance and contribute to the code being set.

5. What are some repair tips for resolving the U0684 code?

- Repair tips may include checking and repairing any damaged wiring, ensuring proper connections, replacing the catalyst temperature sensor if necessary, and clearing the code to see if it returns.

6. Is it safe to continue driving with the U0684 code present?

- It is generally not recommended to continue driving with the U0684 code present, as it can lead to potential damage to the catalytic converter and affect the vehicle's performance.

7. Can resetting the code fix the U0684 issue permanently?

- Resetting the code may temporarily clear the Check Engine light, but if the underlying issue causing the U0684 code is not addressed, it is likely to return.

8. How much does it typically cost to repair the U0684 code?

- The cost of repairing the U0684 code can vary depending on the cause of the issue, but it may involve costs for sensor replacement, wiring repairs, or diagnostic services.

9. Will the U0684 code cause my vehicle to fail an emissions test?

- Yes, having the U0684 code stored in the vehicle's ECM can cause it to fail an emissions test, as it indicates a problem with the catalyst temperature sensor.

10. Can a DIY enthusiast fix the U0684 code at home?

- While some DIY enthusiasts may be able to diagnose and repair the U0684 code at home, it is recommended to have the issue properly diagnosed by a professional to ensure a correct repair.