Audi A6 Air Conditioning Repair
When Mr R brought his Audi A6 to CSN Autos in Wymondham for its scheduled service, he mentioned that the air conditioning had stopped cooling effectively. Assuming it might just need a re-gas, he asked our team to inspect the system as part of the service.
During that visit, our technicians confirmed that the refrigerant level was correct and there were no leaks. Yet still, the A/C wasn’t producing cold air. With the mechanical components in good condition, it was clear that a more complex fault needed deeper investigation.
We arranged for Mr R to return for a dedicated diagnostic appointment, where our award-winning team carried out structured testing using manufacturer data and live signal analysis. What they discovered demonstrated exactly why skill, experience, and precision are vital in diagnosing modern Audi systems.
Is your Audi A6 AC not working? Read on to see how our team in Wymondham identified the fault and restored full cooling performance.
Finding the First Clues in The Audi A6 Air Conditioning Fault
After completing his service, Mr R returned to CSN Autos in Wymondham for a scheduled diagnostic appointment so our team could take a deeper look at why his Audi A6 AC wasn’t working. During the earlier inspection, our technicians had already confirmed that the refrigerant level was correct and that the system was properly sealed.
That ruled out any mechanical faults and indicated that something else was preventing it from operating. Using our diagnostic equipment, we performed a full scan of the vehicle to check for fault codes.
One stood out immediately:
- 00256 – Air Conditioning Pressure/Temperature Sensor (G395): No Signal/Communication
This component, known as the G395 pressure temperature sensor, measures refrigerant pressure and temperature to help the system control compressor operation safely. When no signal is received from this sensor, the vehicle disables the air conditioning function automatically to avoid potential damage.
With refrigerant and mechanical systems confirmed as healthy, our technicians identified two potential causes — either a defective G395 pressure temperature sensor or a fault in the wiring that transmits the signal. The next stage was to begin targeted electrical testing to find where communication had been lost.
Digging Deeper to Find the Hidden Issue
With the fault code identified, our next objective was to determine where the communication link between the G395 pressure temperature sensor and the vehicle’s control system had broken down.
Using Data and Technical Insight
To guide the investigation, our technicians referred to Audi’s official manuals and wiring diagrams. These are the equivalent of a digital roadmap, showing exactly how power, ground, and communication signals are routed through each circuit. Following these diagrams allowed us to see how the G395 sensor connects to the control module through a single communication wire.
Using an oscilloscope, a diagnostic tool that displays live electrical signals, we checked the three key wires at the sensor’s connector:
- Voltage supply: Present and within specification.
- Earth: Stable and correctly grounded.
- Signal: No activity detected.
This result told us that the sensor was receiving both voltage and ground, but couldn’t send data back to the control unit.
Confirming the Results
To verify our findings, we compared readings from another sensor operating on the same communication circuit. Its signal pattern was present, confirming that the control module itself was working correctly. The fault, therefore, had to be somewhere between that connector and the G395 pressure temperature sensor.
Tracing the Circuit
Working methodically along the wiring route, we checked continuity and signal strength at each connection point from the control unit towards the front of the vehicle. The readings remained correct up to a connector positioned behind the passenger-side trim panel. From there, the wiring continues along the nearside wheel arch and beneath the headlamp assembly.
When our technicians carefully opened the protective covering, the problem revealed itself — a corroded section of wire hidden within the main bundle. Moisture had entered the protective sleeve, damaging the copper strands and breaking communication between the sensor and control unit.
With the wiring defect found, we had identified the true cause of the failure: corrosion, preventing signal transmission from the G395 pressure temperature sensor. The next stage was to complete the repair and confirm that communication was fully restored.
Carrying Out the Audi AC Wiring Repair
With the fault identified, our next step was to carry out the repair and secure the wiring against any future moisture damage. Before starting the work, we spoke with Mr R to explain our findings and the repair process in detail. Once he approved the plan, our technicians began the repair.
Accessing the Fault Area
The affected section of wiring had already been exposed during the earlier diagnostic work, where corrosion was found inside the protective sleeve running along the nearside front wheel arch and beneath the headlamp. With that area now fully accessible, our technician prepared the damaged section for repair, ensuring that surrounding wiring and insulation were carefully protected throughout.
Performing the Repair
Following Audi’s official wiring repair standards, our technicians completed the job in several precise steps:
- Cut out the damaged wire on both sides of the corroded section to expose clean copper.
- Installed a new piece of matching-gauge automotive wire to replace the affected length.
- Secured all connections using high-quality crimped and heat-sealed connectors to prevent future moisture ingress.
- Verified circuit continuity to ensure a strong, consistent connection through the entire line.
Testing and Verification
Once the wiring repair was complete, the G395 pressure temperature sensor was reconnected and the stored fault code cleared. Using the oscilloscope again, our technician confirmed that the communication signal had been fully restored. The air conditioning compressor immediately reactivated, and cold air began flowing through the cabin. A final diagnostic scan confirmed that the system was working perfectly and free from faults.
With the repair complete and communication restored, Mr R’s Audi A6 was back to maintaining a consistent, cool temperature — ready for the road once more.
Air Conditioning Restored
For Mr R, the difference was immediate. The air conditioning in his Audi A6 was back to working perfectly, delivering cool, steady airflow throughout the cabin. What began as a difficult-to-trace fault ended with a fully functional, reliable system once more.
Behind that outcome was the skill and attention to detail of our technicians at CSN Autos in Wymondham. Using a structured, data-led approach, they confirmed the issue and carried out the repair exactly as the manufacturer intended. Their methodical process restored full communication between the G395 pressure temperature sensor and the vehicle’s control unit, bringing the system back to life.
This level of diagnostic accuracy takes far more than tools — it demands knowledge, precision, and a deep understanding of modern automotive systems. By combining expertise with advanced testing, our team ensured the problem was fixed correctly and efficiently, saving the customer unnecessary time and expense.
This case highlights what professional diagnostics can achieve. With complex vehicle systems like those found in the Audi A6, accurate testing and technical expertise are what separate a lasting repair from trial and error — and that’s exactly what our award-winning team delivers every day.
Award-Winning Audi Specialists You Can Rely On
When the team at CSN Autos in Wymondham took on this complex air conditioning repair, every step was handled with care From identifying the wiring fault to restoring the system’s communication, our technicians followed a clear, methodical process built on data and expertise.
It’s this proven, evidence-based approach that makes CSN Autos one of Norfolk’s most trusted garages. As winners of the South Norfolk Small Business of the Year 2024, Top Garage Finalist 2023 & 2024, and SME Southern Enterprise Awards Best Auto Repair Centre 2023, we combine advanced diagnostics with genuine customer care.
Here’s what every customer can expect from us:
- Accurate diagnostics and repairs that deliver real savings on dealership costs
- Award-winning technicians with extensive training in complex electrical systems
- Full access to manufacturer-level diagnostic data and repair information
- Transparent communication and honest recommendations from start to finish
- All work backed by a 12-month parts and labour guarantee
- Courtesy cars available to keep you on the road while your car is with us
We’re proud to be recognised for our professionalism and attention to detail. We have a {{average-rating}} star Google rating from {{review-count}} satisfied customers, showing why so many drivers in Wymondham and Norwich trust CSN Autos with their vehicles.
If your Audi A6 AC isn’t working, call CSN Autos in Wymondham today on 01953 425983. Our experienced team will find the true cause and restore your system to perfect working order.
