AutoCodes – Audi – P1909 Audi

P1909 Audi Code - Data Bus ECM 1/2 No Signal From ECM

Quick Answer

P1909 Audi indicates Data Bus ECM 1/2 No Signal From ECM. Common causes include Faulty Engine Control Module (ECM), Engine Control Module (ECM) harness is open or shorted, Engine Control Module (ECM) 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: P1909 Audi indicates Data Bus ECM 1/2 No Signal From ECM.
Common causes: Common causes include Faulty Engine Control Module (ECM), Engine Control Module (ECM) harness is open or shorted, Engine Control Module (ECM) 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 1,574

How popular is this code, among other codes? Low

Repair Importance Level

Urgent (Diagnose now) (3 / 3)

Repair Difficulty Level

Advanced (Pro) (3 / 3)

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Table of contents Created and updated by William Orellana on Sep 27, 2019

Description
Possible Causes
How To Fix
Cost to Diagnose
FAQs
Comments
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Code P1909 Audi Description

OBDII Code P1909 Audi - Data Bus ECM 1/2 No Signal From ECM - AutoCodes.com — P1909 Audi Code - Data Bus ECM 1/2 No Signal From ECM

What does this mean?

What are the Possible Causes of the DTC P1909 Audi?

Faulty Engine Control Module (ECM)
Engine Control Module (ECM) harness is open or shorted
Engine Control Module (ECM) circuit poor electrical connection

How to Fix the DTC P1909 Audi?

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 P1909 Audi 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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Need more information on how to fix the P1909 Audi code? Get Access to Factory Service Manuals

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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 P1909 Audi Code

1. What does OBDII code P1909 mean on an Audi?

P1909 indicates a "Data Bus ECM 1/2 - No Signal From ECM," meaning the Engine Control Module (ECM) is not communicating properly with the vehicle's data bus system.

2. What are the common symptoms of the P1909 code?

Symptoms may include an illuminated check engine light, poor engine performance, reduced fuel efficiency, starting issues, or failure to communicate with diagnostic tools.

3. What causes the P1909 code to appear on an Audi?

Common causes include a faulty ECM, damaged wiring or connectors in the CAN bus system, a failing power supply to the ECM, or software glitches in the ECM.

4. Can I drive my Audi with a P1909 code?

Driving with a P1909 code is not recommended, as it may lead to further engine or communication issues, potentially causing the vehicle to stall or fail to start.

5. How do you diagnose the P1909 code?

Diagnosis involves scanning the vehicle with a diagnostic tool, checking the wiring and connectors for damage or corrosion, and verifying the ECMâ€™s power and ground connections.

6. Is a faulty ECM always the cause of the P1909 code?

No, while a faulty ECM is a possibility, the issue could also stem from damaged wiring, loose connectors, or problems with the CAN bus system.

7. What repairs are typically needed for the P1909 code?

Repairs may involve replacing or repairing damaged wiring, cleaning or reseating connectors, updating or reprogramming the ECM, or replacing the ECM if necessary.

8. How much does it cost to fix the P1909 code on an Audi?

The cost can vary widely depending on the cause, ranging from $100â€“$300 for wiring repairs to $1,000 or more for ECM replacement and programming.

9. Can a software update resolve the P1909 code?

Yes, in some cases, a software update or reprogramming the ECM can resolve the issue if the problem is related to a communication glitch.

10. How can I prevent the P1909 code from returning?

Regular maintenance, inspecting wiring and connectors for damage, and addressing electrical issues promptly can help prevent the P1909 code from reoccurring.