2025 Audi A5 Q5 P01C400 Fuel Rail Pressure Sensor TSB

Symptoms

Owners of affected 2025 Audi A5 and Q5 models, specifically those with the 4-cylinder 2.0 TFSI engine, may observe the "exhaust emissions warning lamp lights up in the instrument cluster". This warning indicates a potential issue with the vehicle's emission control system, prompting the need for diagnosis. This symptom is directly linked to the 2025 Audi A5 Q5 P01C400 issue.

Fault Codes / DTCs

When diagnosing the illuminated exhaust emissions warning lamp, technicians will find specific Diagnostic Trouble Codes (DTCs) logged in the engine control module, identified as control module -J623- (address word 0001). These codes point to a software-related issue concerning the fuel rail pressure sensor.

Code	Description	Symptom Code(s)
P01C400	Fuel Rail Pressure Sensor 1 Range/Performance	46314, 46312

Technical Background

The underlying cause for the 2025 Audi A5 Q5 P01C400 issue is a software anomaly within the engine control unit. This software defect can lead to incorrect readings or interpretations from the fuel rail pressure sensor, triggering the warning lamp and logging the associated DTC P01C400.

Service Procedure Summary

Audi Technical Service Bulletin 2080446/2, which supersedes PSS 2080114, addresses this software issue. To resolve the 2025 Audi A5 Q5 P01C400 fault, the primary repair involves updating the engine control unit software. Technicians should first check if TSB 2079690, titled "00 Combined software update 03.10.00/C (28.13.01) KD2", is applicable for the vehicle. If it is, the software update described in TSB 2079690 must be performed.

The software update process may involve one or several control units in the vehicle to ensure proper functionality and compatibility. During the update, a battery charger must be connected to maintain stable voltage. It is important to note that all part and service references provided in TSB 2080446/2 are subject to change, and technicians should always consult the latest information from their Parts Department and ETKA. The Repair Manual should also be checked for any fasteners, bolts, nuts, and screws requiring replacement during the repair.

Important Warnings for Owners

Audi advises that this software update may neutralize any previous modifications made to the vehicle's software by the owner or other third parties (e.g., tuning or retrofitting). It is crucial for owners to be aware of this potential outcome before proceeding with the update. Furthermore, if a customer chooses to decline the software update, they should be informed that this decision could lead to ongoing issues or restrictions with the use of their vehicle or individual components.

Warranty Information

Warranty claims for this software update are processed according to the Audi Warranty Policies and Procedures Manual. The Service Number for this bulletin is 2470, and the Damage Code is KD02. If the vehicle is outside of any warranty, this Technical Service Bulletin is informational only.

Specific labor operations are available for this repair:

• 0151 0010: For the software update, including connecting the battery charger. This operation should refer to the Service Repair Time (SRT) with associated operations.
• 0151 0040: A fixed rate for the complete software update, which includes all required preliminary and follow-up work. This encompasses tasks such as the bus sleep cycle, calibration drive, additional work, and restarting the software update if flashing is aborted. This operation is allotted 130 Time Units (TU).
• 0150 9999: In cases where additional attempts are required after a flash abort, a lump sum of 50 TU can be claimed per each documented flash cancellation.

All warranty claims must be submitted as per TSB 2080446/2. When performing the combined software update under warranty, time stamps are not required for billing, and technicians are permitted to work on other vehicles simultaneously. The combined software update can also be performed by non-productive personnel.

Source: NHTSA ID 11028461