2025 Audi A5 Engine Warning Lamp On (DTC U041800)
Audi has released Technical Service Bulletin 2078871/1 for 2025 A5, Q5, S5, and SQ5 models experiencing an engine warning lamp (MIL) illuminated with diagnostic trouble code U041800. This TSB addresses an implausible signal from the ABS control module due to low voltage.
Si applica anche a
- Audi Q5
- 2025
- Audi S5
- 2025
- Audi SQ5
- 2025
Owners of 2025 Audi A5, Q5, S5, and SQ5 models may notice the "Engine warning lamp (MIL) on" in their instrument cluster. This condition is often accompanied by Diagnostic Trouble Code (DTC) U041800. Audi Technical Service Bulletin (TSB) 2078871/1 addresses this specific issue, which involves an implausible signal from the ABS control module.
Symptoms
Vehicle owners may observe the following:
- The "Engine warning lamp (MIL) on" illuminates on the dashboard.
- Malfunction display symbols related to "emissions control system malfunction display" or "engine management malfunction display (diesel)" may appear.
Fault Codes / DTCs
When scanned, the vehicle's diagnostic system may log the following code:
- DTC: U041800
- Description: "ABS Control Module, implausible signal"
- Symptom Code: 487509
- Diagnostic Address: 812C
Diagnosis and Trigger Conditions
This 2025 Audi A5 engine warning lamp issue is typically triggered when signals from the ABS control unit are provided with a delay. This delay can activate the warning lamp if the electrical system voltage drops below 12V. It's important to note that after a bus sleep cycle, the engine warning lamp may no longer be on, making the complaint difficult to reproduce during a workshop visit.
Important Warnings for Owners
Audi has stated that billing to TSB 2078871/1 is not permitted. This indicates that the service information is for support during work, but specific warranty claims might need to follow other procedures. Additionally, the measures on how to correctly provide the signals and revise the warning messages are currently in development by Audi.
Repair Procedure Summary
For a 2025 Audi A5 engine warning lamp illuminated with DTC U041800, technicians should ensure a 12V power supply is maintained on the vehicle. After confirming adequate voltage, the DTC U041800 should be cleared. The original customer complaint may have been resolved by a bus sleep cycle, but the vehicle should be re-evaluated based on any clear, persistent complaints.
Owner Action
If you experience the "Engine warning lamp (MIL) on" or any related malfunction display messages on your 2025 Audi A5, Q5, S5, or SQ5, it is recommended to visit an authorized Audi service center. While the issue might clear itself after a bus sleep cycle, a professional diagnosis can confirm the presence of DTC U041800 and address the underlying cause. Be aware that the manufacturer's long-term solution for signal provision and warning message revision is still under development.
Source: NHTSA ID: 11022654
Frequently Asked Questions
- What does DTC U041800 mean for my 2025 Audi A5?
- DTC U041800, specifically "ABS Control Module, implausible signal," indicates that the ABS control unit is sending delayed signals, which can trigger the engine warning lamp, especially if your vehicle's electrical system voltage is below 12V.
- Why is my 2025 Audi A5 engine warning lamp on?
- According to Audi TSB 2078871/1, the 2025 Audi A5 engine warning lamp can illuminate due to an implausible signal from the ABS control module, often linked to low electrical system voltage. This can also manifest as "emissions control system malfunction display" messages.
- Will the engine warning lamp on my Audi clear itself?
- The engine warning lamp associated with DTC U041800 may temporarily clear itself after a bus sleep cycle. However, it is advisable to have your vehicle inspected by an Audi service center to address the root cause and ensure proper system function.
- Can I be charged for the repair related to TSB 2078871/1?
- Audi's TSB 2078871/1 states that billing to this specific TSB number is not permitted. This suggests that while the bulletin provides guidance, the warranty coverage for the actual repair may fall under standard warranty terms or other service actions. It's best to discuss this with your Audi dealer.
Altre revisioni di questo TSB
What Audi A5 owners report
Counted from the records in our database across 19 model years.
- 377
- Owner complaints
- 22
- Recalls
- 4,447
- Service bulletins
- 9
- Crashes reported
- 3
- Fires reported
- 6
- Injuries reported
The 2025 model year
9 complaints, the 10th most of 19 model years on file. Owners reported 0 crashes, 0 fires and 0 injuries for this year, which also has 2 recalls on file.
Engine, the system this article covers, accounts for 68 of 377 complaints (18%), including 2 for 2025.
Complaints by model year
| 2009 | 11 | |
|---|---|---|
| 2010 | 50 | |
| 2011 | 39 | |
| 2012 | 36 | |
| 2013 | 38 | |
| 2014 | 29 | |
| 2018 | 38 | |
| 2019 | 12 | |
| 2020 | 60 | |
| 2025 | 9 |
Most-reported systems
- Air Bags — 91
- Electrical System — 82
- Engine — 68
- Steering — 27
- Back Over Prevention — 18
Latest recalls for the 2025 model year
- 25V899000 — Seat Belts (Dec 2025)
- 25V638000 — Seat Belts (Sep 2025)
Recent owner reports about engine
The contact owns a 2025 Audi A5. The contact stated that while driving approximately 45-50 MPH, the vehicle suddenly decelerated without warning to approximately 20 MPH.
Read owner complaints →The contact owns a 2025 Audi A5 Sportback. The contact stated that while his wife was driving at an undisclosed, the vehicle was stopped, and then the vehicle stalled.
Complaints are owner reports filed with NHTSA. They are unverified, and counts depend on how many vehicles were sold, so they are not a failure rate.
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