2021 Audi Q7, Q8, A8, S8 Red Coolant Warning Lamp TSB

Audi has released Technical Service Bulletin (TSB) 2062951/2 to address instances where the "Red coolant warning lamp" illuminates in the instrument cluster of certain 2021 Audi vehicles. This TSB supersedes an earlier bulletin, Group 19 number 21-16, dated May 3, 2021.

The issue is typically accompanied by specific Diagnostic Trouble Codes (DTCs) stored in the Engine Control Module (ECM), J623. Owners of affected 2021 Audi Q7, Q8, A8, and S8 models should be aware of these symptoms and the recommended repair procedure.

Symptoms

Owners may observe the following symptom:

• "Red coolant warning lamp is illuminated in the instrument cluster."

Fault Codes / DTCs

When the "Red coolant warning lamp" is active, the following DTCs may be stored in the Engine Control Module (ECM), J623 (address word 0001):

DTC Code	Description
P218100	Malfunction in cooling system
P017B00	Cylinder head temperature sensor implausible signal
P017C00	Cylinder head temperature sensor short circuit to ground
P017E00	Cylinder head temperature sensor open circuit/loose contact

Technical Background

The root cause of the red coolant warning lamp and associated DTCs is often damage to the O-ring of the coolant temperature sender G407, also known as the cylinder head temperature sensor. This damage can lead to water intrusion inside the sensor's plastic housing, which then damages the sensor element itself. The malfunction of the sensor can occur sporadically.

Diagnosis and Repair Procedure Summary

To diagnose and resolve the issue, technicians should follow a specific procedure:

1. Guided Fault Finding: Begin by working through the Guided Fault Finding process to accurately identify the problem.
2. O-ring Inspection: It is crucial to visually inspect the O-ring located directly on the tip of the coolant temperature sender G407 for any visible damage or pinching. An image in the TSB (Figure 1) illustrates a pinched O-ring.
3. Sensor Replacement: If the G407 sensor's O-ring is found to be damaged or pinched, the coolant temperature sender G407 must be replaced.

Required Tools or Parts

For the repair, the following parts and tools are specified:

• Coolant temperature sender G407: Quantity 01. Always check with the Parts Department for the latest information.
• Fasteners, Bolts, Nuts, and Screws: As needed per the Repair Manual (refer to ETKA/ELSA).
• VAS 6160/VAS 6150: A VAS tester with the current version of ODIS (Windows 10) is required for diagnostic procedures.

Warranty Information

This repair is covered under warranty with specific claim types and conditions:

• Claim Type 110: Applicable for vehicles up to 48 months or 50,000 miles.
• Claim Type G10: For Certified Pre-Owned (CPO) vehicles, verification of owner status is required.
• The Service Number for this procedure is 1978, and the Damage Code is 0040.
• All warranty claims must adhere to the Audi Warranty Policies and Procedures Manual and are subject to review or audit by Audi Warranty.

Important Warnings

Owners should be aware that if their vehicle is outside of its warranty period, this Technical Service Bulletin is provided for informational purposes only. This means the repair costs may not be covered by Audi.

NHTSA ID: 10224789