Q5 IAT Sensor Issue Causing Rough Engine & Power Loss

I had a similar issue with my 2012 Q7 last winter. As someone with basic DIY maintenance experience, I initially tried using a diagnostic tool to confirm the IAT sensor error code. The symptoms matched yours exactly, rough running engine, reduced power, and the check engine light. The air temperature readings were way off, causing the engine management system to run a richer fuel mixture than needed. I took it to my regular workshop where they confirmed the intake air sensor was defective. The repair was straightforward, they replaced the IAT sensor and cleared the error codes. Total cost was 155 Euro including parts and labor. The car has been running perfectly since then. Could you share some additional details about your Q5: Engine size, Approximate mileage, Does the rough running occur more during cold starts, Have you noticed any changes in fuel consumption This information would help determine if your situation is similar to what I experienced. These sensors typically start failing gradually, but getting it fixed sooner rather than later prevents potential fuel efficiency issues and keeps the engine running optimally.

Thanks for sharing your experience. My Q5 has 52682 KM since the last service. The rough running is definitely worse during cold starts, and fuel consumption has increased by about 15% in the last month. The IAT sensor symptoms you described match my situation perfectly. The engine issues seem most noticeable when the temperature sensor is likely struggling during cold weather. The car diagnostics also showed similar error codes to what you mentioned. Based on the repair cost you shared, this seems like a reasonable fix to pursue. Were there any other checks the workshop did before confirming it was just the air sensor that needed replacement?

Thanks for those additional details. The symptoms and diagnostic codes you're describing are nearly identical to what I experienced with my Q7. The workshop did perform a few additional checks before replacing my IAT sensor. They specifically: Tested the wiring harness connecting to the temperature sensor, Checked for any air leaks around the intake manifold, Monitored live sensor data using their diagnostic tool to verify erratic readings In my case, the live sensor readings were clearly incorrect compared to actual ambient temperatures, confirming the faulty IAT sensor diagnosis. The increased fuel consumption you mentioned (15%) matches what I experienced, this happens because incorrect temperature readings cause the engine management system to miscalculate the proper fuel mixture. The cold start issues are also a classic symptom of a failing air sensor. When I had mine replaced, the technician mentioned these sensors often show their worst behavior during cold weather when accurate temperature readings are most critical. The 155 Euro repair resolved all issues, the rough running, excess fuel consumption, and cold start problems disappeared immediately after the new IAT sensor was installed. Given your matching symptoms and similar vehicle platform, you're likely looking at the same straightforward fix.

Based on everything you shared, I feel more confident moving forward with the IAT sensor replacement. The fact that your repair fixed the cold start issues and fuel consumption problems is particularly encouraging since these match my symptoms exactly. The additional checks your workshop performed make sense, testing the wiring, checking for intake leaks, and monitoring the intake air temperature readings seems like a thorough approach. The diagnostic tool readings showing erratic air sensor behavior in my case align with what your technician found. I will schedule an appointment with my workshop and make sure they perform those same verification steps before replacing the temperature sensor. The 155 Euro repair cost seems reasonable considering the potential fuel savings and preventing any long-term engine issues. Thanks for confirming all the details about your repair experience. It helps knowing that replacing the faulty sensor completely resolved similar symptoms on a comparable vehicle.