2017-2025 Audi A3 S3 TT TTS Gearbox Fault P174A00 P174E00

Audi has issued Technical Service Bulletin (TSB) 2077475/1 to address a common issue affecting various models from 2017 to 2025, including the Audi A3, S3, TT, and TTS. Owners may observe a "gearbox fault warning light on" in the instrument cluster, often accompanied by specific diagnostic trouble codes (DTCs) related to the transmission's mechatronic unit.

This TSB provides a detailed procedure for diagnosing and repairing the underlying electrical malfunction, ensuring the proper function of the transmission. If you own an affected Audi S3 gearbox P174A00 issue, understanding this bulletin can help you communicate effectively with your service center.

Symptoms

Owners of affected Audi vehicles may notice the following:

• A "gearbox fault warning light on" appearing in the instrument cluster.
• A "transmission malfunction display" message.

It is important to note that, despite these warnings, there are typically no noticeable issues with the gear-change characteristics of the gearbox itself.

Fault Codes / DTCs

Technicians will find specific diagnostic trouble codes (DTCs) logged in the Transmission Electronics -J217- control unit (address word 0002). This TSB specifically applies to the following codes:

• P174A00: Valve 3 in partial transmission 1 electrical malfunction (Symptom: 10739)
• P174E00: Valve 3 in partial transmission 2 electrical malfunction (Symptom: 10740)

For this TSB to be applicable, the frequency counter for these DTCs in the "Standard Ambient Conditions" must be at least 2.

Diagnosis / Trigger Conditions

Diagnosis for this issue begins when a customer reports the gearbox warning light. A technician will confirm the customer's statement and verify that the gear-change characteristics are unaffected. The key diagnostic step involves checking for the presence of DTC P174A00 or P174E00 in the Transmission Electronics -J217- module. Crucially, the TSB specifies that the symptom number must be either 10739 (for P174A00) or 10740 (for P174E00), and the frequency counter in the standard ambient conditions must be 2 or greater. If these conditions are not met, the TSB does not apply, and further diagnosis using Guided Fault Finding is required.

Important Warnings for Owners and Technicians

Audi highlights several critical points within TSB 2077475/1:

• Applicability: This TSB only applies if the symptom number (10739 or 10740) and a frequency counter of at least 2 are stored in the event memory. If the DTCs P174A00 or P174E00 have different symptom numbers or a frequency counter of 1, this TSB does not apply, and repair costs cannot be invoiced under its terms.
• Electrostatic Discharge (ESD): Electrostatic charge can cause irreparable damage to electrical components within the mechatronic unit. Technicians must use an ESD workplace (VAS 6613) and avoid direct contact with electrical components.
• Cleanliness: Hair or dirt particles can severely restrict the mechatronic unit's function or cause it to fail. The highest levels of cleanliness are required during all work on the mechatronic unit, ensuring no foreign particles enter the system.
• Parts and Assembly: To maintain cleanliness, assembly work on the transmission should only be performed after all required genuine parts have been received and completed in a single work sequence. It is also essential to ensure that all contacts are correctly inserted and not bent when fitting the new contact plate.

Repair Procedure Summary

The repair for the Audi S3 gearbox P174A00 or P174E00 issue primarily involves replacing the mechatronic unit contact plate. The general steps are:

1. Initial Diagnosis: Read and compare event memory entries in the transmission control unit using Guided Fault Finding.
2. Preparation: Unscrew the oil drain plug on the mechatronic unit and drain the oil.
3. Disassembly: Remove the mechatronic unit cover and then unscrew the securing bolts for the contact plate.
4. Contact Plate Replacement: Carefully detach the old contact plate. Fit the new contact plate (part number 0GC 927 709 A), ensuring all contacts are properly engaged and not bent.
5. Reassembly: Tighten the new contact plate in two stages using new securing bolts (N 904 552 02) according to a specific sequence (1 -> 2 -> 3 -> 12 -> 5 -> 4 -> 11 -> 10 -> 9 -> 8 -> 6 -> 7) and torque specifications (Stage 1: 2 Nm; Stage 2: 3 Nm + 30°).
6. Final Steps: Fit a new cover for the mechatronic unit (0GC 325 201) with new bolts (N 910 327 02), check and fill the gearbox oil (G 055 529 A2), and perform a road test to confirm the complaint is rectified. If the issue persists, further Guided Fault Finding is necessary.

Required Tools or Parts

To perform this repair, the following special tools and genuine parts are required:

• Special Tool: ESD workplace -VAS 6613-
• Parts:
  • Contact plate: 0GC 927 709 A (Quantity: 1)
  • Bolt for contact plate: N 904 552 02 (Quantity: 12)
  • Cover for mechatronic unit: 0GC 325 201 (Quantity: 1)
  • Bolt for cover for mechatronic unit: N 910 327 02 (Quantity: 4)
  • Gear oil: G 055 529 A2 (Quantity: As per Workshop Manual)
  • Retaining clip: 0BH 325 147 (Quantity: 1)
  • Seal: N 043 809 2 (Quantity: 1)

Warranty Information

For vehicles still under warranty, claims must adhere to the Audi Warranty Policies and Procedures Manual. The TSB provides specific codes for warranty claims:

• Service Number: 3878
• Damage Code: 0010
• Labor Operations:
  • Remove and install mechatronic unit cover: 3460 19xx
  • Repair mechatronic unit: 3511 4199 (40 Time Units)
  • Guided Fault Finding (GFF): 1050 0060
  • Charge Battery: 2706 8950
• Claim Comment: As per TSB 2077475/1

If the vehicle is outside of its warranty period, this Technical Service Bulletin is for informational purposes only, and repair costs may not be covered.

NHTSA ID: 11017610