Audi A5 Fan Failure Leads to Engine Overheating

I had a similar vehicle overheating issue with my 2017 Audi A4 2.0 TFSI last summer. Having some experience with engine cooling systems, I first noticed the temperature control issues during stop-and-go traffic. The symptoms matched yours exactly, the radiator fan was barely engaging, leading to higher than normal engine temperatures. After running diagnostics, my workshop found a damaged wiring connector going to the fan control module. The constant engine bay heat had made the plastic connector brittle, causing intermittent connection issues. The repair involved replacing the wiring harness connector and testing the fan operation at different temperature thresholds. Total cost was 95 Euro for parts and labor. Since the fix, the electric fan kicks in properly and temperature stays normal. Before jumping to conclusions about the fan motor itself, have you noticed any check engine lights? Also, when was your last coolant service? These details would help narrow down if you're dealing with the same electrical issue or potentially something else in the cooling system. Could you share: Current mileage on your A5, Any warning lights on the dash, When the problem first started, If the issue occurs more during specific driving conditions This information would help determine if your case matches what I experienced.

Last service was at 20000 KM and I am currently at 22151 KM. After checking the OBD, no error codes were found. The vehicle overheating started about 2 weeks ago, first noticed during city driving when temperatures were quite high. The electric fan behavior seems most concerning, it only activates when the engine temperature is already too high. Coolant levels are good and the system shows no visible leaks. Given the low mileage and regular maintenance schedule, a damaged connector like in your case could definitely be the culprit. Good to know the repair costs were reasonable if it turns out to be a similar wiring issue affecting the radiator fan operation.

Thanks for providing those details about your A5. Your situation sounds very similar to what I experienced, especially the fan engaging too late. The low mileage and recent service actually strengthen my suspicion about the wiring connector being the issue. When my A4 had this problem, the lack of error codes initially made diagnosis tricky. The electric fan would only kick in when temperatures were already critical, just like yours. A visual inspection of the connector revealed slight discoloration from heat exposure, something easily missed unless specifically looking for it. My mechanic explained that these connectors can deteriorate without triggering fault codes, since the connection is intermittent rather than completely failed. The radiator fan might still function, just not at the correct temperature thresholds. Given you are experiencing identical symptoms with similar timing after a service, I would recommend having your workshop specifically check the fan control module wiring harness. In my case, the new connector resolved the overheating completely, and the cooling system has worked flawlessly since. The repair should be similarly priced for your A5, likely around 100 Euro depending on labor rates. Make sure they test the fan clutch operation at different temperatures after the repair to confirm proper engagement points.

Thanks for all that detailed information about the connector issue. It definitely makes sense given my symptoms. I will book the car in next week and specifically ask them to inspect the fan control module wiring harness since the radiator fan behavior matches your experience exactly. The 100 Euro repair cost sounds much better than potentially replacing the entire electric fan motor. Since my vehicle overheating issues started so suddenly without any warning lights, a deteriorated connector seems the most likely cause. The timing after my recent service is also quite similar to your case. Will update once the workshop has checked the wiring and tested the fan operation. Really hoping for a straightforward fix like yours rather than major cooling system repairs. Thanks again for sharing your diagnosis process, it has helped narrow down where to start looking.