2021-2024 Audi Coolant Leak & P0299 DTC TSB 2070349/5

Audi has released Technical Service Bulletin (TSB) 2070349/5 to provide guidance for diagnosing and repairing coolant loss, warning lamp illumination, and diagnostic trouble code (DTC) P0299 in various 2021-2024 Audi models. This TSB, most recently revised on December 1, 2025, helps technicians identify and resolve issues related to the mechanical coolant pump and associated vacuum system components.

This bulletin specifically applies to 2021-2024 Audi Q8, S4, S5, RS 5, A6, A6 allroad, S6, A7, S7, SQ5, and Q7 vehicles equipped with 2.9L or 3.0L V6 TFSI engines. Owners experiencing an Audi coolant leak P0299 or related symptoms should be aware of this service information.

Symptoms of an Audi Coolant Leak

Owners of affected Audi vehicles may observe one or more of the following symptoms:

• Coolant loss/leak: Visible signs of coolant leaking from the vehicle.
• Coolant warning lamp: An illuminated warning light on the instrument cluster indicating low coolant levels or a cooling system issue.
• Engine warning lamp on: The check engine light may illuminate, sometimes in conjunction with other coolant-related issues.

Associated Fault Codes

In addition to the visible symptoms, a diagnostic scan may reveal specific fault codes. The TSB notes that the DTC "P0299: Turbo/Super Charger Underboost" may be logged. This can occur if the changeover valve N649 is impaired by coolant entering the vacuum system, leading to functional restrictions.

Understanding the Audi Coolant Leak P0299 Issue

Workshop findings indicate that the mechanical coolant pump is frequently the source of the leak. However, it's crucial to distinguish between a genuine leak and normal operational conditions. For instance, traces of coolant (small quantity) on the drip cup, as illustrated in Figure 1 of the TSB, are considered normal. Up to 3 ml of coolant may escape over 100 hours of operation due to lubrication and cooling of the seal, and this does not constitute a reason for a complaint.

Similarly, dried deposits on the vacuum connection, shown in Figure 2, are not a clear indication of a leak. Technicians are advised to precisely locate the leak to avoid repeat or incorrect repairs. It's also important to ensure that any coolant level drop isn't merely due to insufficient bleeding from a previous repair.

Important Warnings for Owners and Technicians

Audi provides several critical advisories within TSB 2070349/5:

• Warranty Claims: "If the vehicle is outside of any warranty, this Technical Service Bulletin is informational only."
• Repair Accuracy: "Try to reproduce the customer complaint (based on the description/cause of the issue), so that it can be clearly assigned to this TSB. The following repair must only be carried out if all the criteria (model/type, chassis number, engine/motor, gearbox code, PR number(s), part number, software version, code, etc.) apply exactly. Otherwise, this solution will not eliminate the problem and repeat repairs may be necessary. In such a case, the warranty claim may be rejected, and the cost of the parts may be charged back."
• Documentation: "Documentation is required" for certain repair steps, particularly when replacing components due to leaks, including photographing the production date of the coolant pump if it is found to be leaking (as shown in Figure 4).

These warnings emphasize the importance of accurate diagnosis and adherence to the TSB's guidelines to ensure effective repair and proper warranty coverage.

Diagnosing the Coolant Leak

Diagnosing the Audi coolant leak P0299 issue involves a systematic approach. Technicians are instructed to assess the leak using the following steps:

1. Check Vacuum Line and Valve N649: Inspect the vacuum line and changeover valve N649 (Checkpoint 1 in Figure 3, a diagram of vacuum system checkpoints) for any traces of coolant. This requires disconnecting these components.
   • If coolant traces are visible, the mechanical coolant pump should be replaced.
   • If no coolant traces are visible, proceed to the next step.
2. Clean and Dry: Thoroughly clean and dry any suspected leak areas and traces of coolant.
3. Fill Cooling System: Fill the cooling system to its maximum level.
4. Visual Check: Perform a visual inspection to assess for leaks at both idling speeds and higher engine speeds (approximately 2500 rpm).
5. Cooling System Leak Check: Utilize the workshop manual (ELSA) to check the cooling system for leaks.
6. Reassess Leak: Re-evaluate the suspected leak.
   • If no coolant leak is detected during the test, further observation of the vehicle is recommended, and no parts replacement is necessary.
   • If a coolant leak is detected, the component causing the damage must be replaced. All leaks must be documented with photos or videos. If the coolant pump is the source, its production date (Figure 4) should also be photographed.

Repair Procedure Summary

If a leak is confirmed, the repair procedure outlined in TSB 2070349/5 focuses on replacing the faulty components and ensuring the integrity of the vacuum system. The TSB provides detailed instructions for technicians to follow.

1. Mechanical Coolant Pump Replacement: If traces of coolant are found at the vacuum line or valve N649, or if the coolant pump is identified as the source of the leak after thorough testing, the mechanical coolant pump must be replaced.
2. Vacuum System Inspection and Repair: The leak from the coolant pump can potentially contaminate other components of the vacuum system. Technicians must systematically check checkpoints 2 and 3 (Figure 3) for coolant residue. These checkpoints include the connection to vacuum line N645/coolant shut-off valve and the vacuum distributor in the area of the vacuum pump.
   • If fresh coolant is found, contaminated components such as the entire vacuum line, valve N545, coolant shut-off valve, and vacuum reservoir must be replaced. An attachment (ea839_vacuum_system.pdf) provides a precise overview of the vacuum system components.
   • If no coolant residue is visible at checkpoints 2 and 3, only the changeover valve N649 should be replaced, and the vacuum line between the coolant pump and valve N649 should be cleaned using compressed air.

Warranty Information

For warranty claims related to TSB 2070349/5, Audi specifies a Service Number of 1950 and a Damage Code of 0050. The bulletin details various labor operations with associated Standard Repair Times (SRT) and Technical Units (TU) for tasks such as removing and installing noise insulation, checking and topping up coolant, checking for leaks, and replacing specific components like the coolant pump, regulating valves N649 and N545, vacuum pump, and various vacuum reservoirs depending on the specific model and engine configuration. All warranty claims must adhere to the Audi Warranty policies and Procedures Manual.

Additional Information

Audi reminds technicians that all part and service references in TSB 2070349/5 are subject to change. It is essential to consult the Parts Department and/or ETKA for the latest information. The Repair Manual should also be checked for any fasteners, bolts, nuts, and screws that require replacement during the repair process.

NHTSA ID: 11027324