AutoCodes – Generic – U1140

U1140 Code - Lost Communication With Active Exhaust Valve 2

Quick Answer

The purpose of the Active Exhaust Valves is to reduce exhaust noise in order to comply with pass-by noise regulations. Common causes include Faulty Active Exhaust Valve Actuator, Active Exhaust Valve Actuator harness is open or shorted, Active Exhaust Valve Actuator 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: U1140 indicates Lost Communication With Active Exhaust Valve 2.
Common causes: Common causes include Faulty Active Exhaust Valve Actuator, Active Exhaust Valve Actuator harness is open or shorted, Active Exhaust Valve Actuator 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 21,952

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 02, 2024

Description
Possible Causes
How To Fix
Cost to Diagnose
Comments
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Code U1140 Description

The purpose of the Active Exhaust Valves is to reduce exhaust noise in order to comply with pass-by noise regulations. The Active Exhaust Valves system consists of two main components. The first is the mechanical butterfly valves, which are welded into the exhaust pipe on each bank. Attached to each valve is a smart actuator. These are connected to the mechanical valves via a transmission spring to help reduce heat transfer from the butterfly valves to the actuators.
The Active Exhaust Valve actuators communicate with the Powertrain Control Module (PCM) over a LIN Bus circuit. Each Active Exhaust Valve actuator, one for the left (actuator 1) and one for the right (actuator 2), has a unique part number/internal ID. The PCM can identify each actuator's location by this unique ID. Based on engine torque, rpm, and vehicle speed, the PCM sends position commands to the Active Exhaust Valve actuators. These actuators then move the butterfly valves to the commanded positions. An internal Hall Effect sensor counts the pulses to determine the valve position. The valve actuators are calibrated at every Key-ON event; the PCM sends full open and full closed commands and checks the actual position against the commanded position. If calibration is unsuccessful for any reason, the actuators self-diagnose and report fault flags to the PCM over the LIN Bus.
If the valve position does not match the predetermined calibration, a performance code is set, and the valves will default to the full open position. If an actuator is not attached to the mechanical valve, or if the transmission spring is broken or missing, the actuator will continue to rotate indefinitely and set a fault. Additionally, if the mechanical valve is stuck and cannot move, a fault will be set.

OBDII Code U1140 - Lost Communication With Active Exhaust Valve 2 - AutoCodes.com — U1140 Code - Lost Communication With Active Exhaust Valve 2

What does this mean?

What are the Possible Causes of the DTC U1140?

Faulty Active Exhaust Valve Actuator
Active Exhaust Valve Actuator harness is open or shorted
Active Exhaust Valve Actuator circuit poor electrical connection
Faulty Powertrain Control Module (PCM)

How to Fix the DTC U1140?

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 U1140 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 U1140 code?

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Need Help with the Code?

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Information for Specific Makes

U1140 Chrysler — Lost Communication With Active Exhaust Valve 2
U1140 Dodge — Lost Communication With Active Exhaust Valve 2
U1140 Jeep — Lost Communication With Active Exhaust Valve 2
U1140 RAM — Lost Communication With Active Exhaust Valve 2

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.