2008 VW Passat P2181 Code: Check Engine Light On Only When AC Is Turned On
I own a 2008 Volkswagen Passat 2.0T with 108,000 miles. I'm currently receiving a P2180 fault code (OBD-II code P2181). The issue only occurs when the air conditioning is turned on—within minutes of turning it on, the check engine light illuminates. Engine temperature and overall performance appear normal. I recently had a timing belt replaced, and I'm wondering if the technician may have accidentally disconnected or damaged the slow-speed fan wiring during that service. Could this be related to the P2181 code? Any insight would be greatly appreciated.
Without other diagnostic codes pointing to a circuit fault, a faulty thermostat is less likely. However, it's important to inspect the sensor wiring and connectors carefully. Make sure you know exactly where the P2181 sensor is located—this can help identify potential issues. For visual guidance, check this video: https://www.youtube.com/watch?v=L1bCJvHsyQ0