Experiencing an issue where your Audi A6 won’t start can be incredibly frustrating, especially when the Multi Media Interface (MMI) system and your OBD2 scanner seem to be functioning normally. This situation, where you turn the key or press the start button and are met with silence despite some electrical systems working, is a common concern for Audi A6 owners. Let’s delve into the possible causes and troubleshooting steps when your audi a6 won’t start mmi works obd2 system is responsive.
If you’re facing this exact problem, you’re likely experiencing symptoms similar to this: you insert the key, and everything seems to lose power momentarily. Key stuck in the ignition, no engine noise when turning the key, no dashboard lights illuminating, and the steering wheel locked. Yet, after disconnecting and reconnecting the battery, the issue temporarily resolves itself. This intermittent problem can be baffling, particularly when it recurs frequently.
One owner of a 2009 Audi A6 Quattro Premium Plus reported these exact symptoms, along with a history of MMI issues and a series of OBD2 error codes. These codes provide valuable clues to the underlying problem and can guide our troubleshooting process.
Here are the OBD2 error codes reported:
- 0007 – Display Control Unit
- 00384 – Optical data bus
- 01320 – Climatronic control module
- 01330 – Comfort system central control module
- 00457 – Vehicle electrical system control module
- 01964 – Memory Seat Control Module / Steering column adjustment
- 00532 – Supply voltage
- 0008 – Air Conditioning
- 00797 – Sunlight photo sensor
- 0019 – Gateway
- 02230 – Radio tuner digital
- 02256 – Static Current
- 03041 – Energy management active
- 0042 – Door Electronics Driver side
- 01705 – Mirror Selector switch
- 0046 – Central Module Comfort System
- 01134 – Alarm horn (disconnected)
- 0047 – Sound System
- 00870 – Left front bass speaker
- 0052 – Door Electronics Passenger Side
- 00920 – Heated outside mirrors
These codes paint a picture of a broader electrical system issue, rather than a simple starter motor failure. The presence of codes related to various control modules such as the Display Control Unit, Comfort System, Vehicle Electrical System, and Gateway, along with “Supply Voltage” and “Energy management active” errors, suggests a problem with power distribution or a central control module malfunction.
Potential Causes and Troubleshooting Steps
When your Audi A6 won’t start but the MMI and OBD2 are working, consider these potential culprits:
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Battery Issues: While disconnecting and reconnecting the battery temporarily resolves the issue, it doesn’t rule out battery problems. A battery with low voltage or internal resistance could cause intermittent electrical failures, especially under the high current demand of starting the engine.
- Action: Test the battery voltage with a multimeter. Check for proper voltage (around 12.6V when fully charged and at rest) and perform a load test to assess its capacity under load.
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Loose or Corroded Battery Terminals: Poor connections at the battery terminals can disrupt power flow.
- Action: Inspect and clean battery terminals and cable clamps. Ensure they are tight and free of corrosion.
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Faulty Ignition Switch: The ignition switch is responsible for initiating the starting sequence. A failing switch might not consistently send power to all necessary systems.
- Action: While diagnosing an ignition switch can be complex and often requires professional equipment, you can check for any obvious signs of damage or looseness. This is often best left to a qualified technician.
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Starter Motor or Solenoid: Although less likely given the broader electrical symptoms, a failing starter motor or solenoid could be the issue. However, usually, a starter motor issue wouldn’t explain the loss of power to other systems and the range of error codes present.
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Vehicle Electrical System Control Module (J519): Error code “00457 – Vehicle electrical system control module” directly points to this module. This module manages various electrical functions, and its malfunction could explain the widespread electrical issues and starting problems.
- Action: This usually requires professional diagnostic equipment to test and potentially replace or reprogram the module.
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Comfort System Central Control Module (J393): Code “01330 – Comfort system central control module” also indicates a potential issue with this module. It controls features like central locking, alarm system, and interior lighting, and its malfunctions can sometimes interfere with starting.
- Action: Similar to the J519, diagnosing and resolving issues with the J393 module often requires professional intervention.
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Power Supply Relays and Fuses: Faulty relays or blown fuses in the power supply circuits can cut off power to critical systems needed for starting.
- Action: Check the fuses and relays related to the engine management system and starting system. Refer to your Audi A6 owner’s manual for fuse box diagrams.
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Immobilizer System: Although the MMI is working, a glitch in the immobilizer system could prevent the engine from starting. However, immobilizer issues often present different symptoms and might display specific warning lights.
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Wiring Harness Issues: Damaged or corroded wiring harnesses can cause intermittent electrical problems.
- Action: Inspect accessible wiring harnesses for any signs of damage, especially in areas prone to moisture or physical stress.
OBD2 and MMI Functionality
The fact that your MMI system works and your OBD2 scanner can communicate with the car indicates that the CAN bus network and some essential electrical systems are still operational. This is crucial information because it narrows down the problem. If the MMI and OBD2 were also dead, it would point towards a more fundamental power supply issue affecting the entire vehicle.
Next Steps
Given the complexity of the error codes and the intermittent nature of the problem, professional diagnosis is highly recommended. A qualified Audi technician can use specialized diagnostic tools to further investigate these error codes, test the control modules, and pinpoint the root cause of your audi a6 won’t start mmi works obd2 issue.
Attempting to resolve complex electrical issues without proper training and equipment can be risky and might lead to further complications. Seeking expert help will ensure accurate diagnosis and effective repair, getting your Audi A6 back on the road reliably.
