VW Up Engine Temp Issues, Cooling System Troubleshoot

Having some experience with VW cooling systems, I faced similar thermal management issues with my 2019 VW Polo. The symptoms were nearly identical, inconsistent engine temperature readings and delayed warm-up times. After taking it to the workshop, they found a blown fuse controlling the engine cooling system sensors. The defective fuse was causing erratic temperature readings and triggering the check engine light. The repair was straightforward and cost 52€ including diagnostic and replacement. However, your situation might be different, as automotive cooling problems can have various causes. Could you share: Current mileage, Any recent maintenance work, Whether the coolant level is normal, If you notice any unusual sounds from the engine bay This would help determine if your car is experiencing the same issue or if there might be other factors affecting the engine cooling system. While a blocked cooling grille could cause problems, the combination of symptoms you describe points more toward an electrical or sensor issue.

Thanks for the feedback. My Up has 39857km and just had its annual service last month. The coolant level appears normal and I dont hear any unusual noises. The radiator blockage theory came after noticing some debris buildup behind the cooling grille. The thermal management system seems to be struggling most during city driving. After reading about your fuse experience, I checked the fuse box but all cooling system related fuses look intact. The workshop quoted 90€ just for diagnostics which seems steep. Did your repair include any cooling system pressure testing or radiator flow checks?

Thanks for the additional details. Like you, I was initially hesitant about diagnostic costs when my Polo had similar issues. The 90€ quote is actually reasonable considering the complexity of modern engine cooling systems. My repair did include pressure testing of the cooling system, which helped rule out any physical blockages or leaks. While the debris you noticed behind the cooling grille should be cleaned, the symptoms you describe, particularly the slow warm-up and erratic temperature readings, strongly suggest an electronic rather than mechanical issue. In my case, what appeared as intact fuses still turned out to be problematic. The workshop found microscopic breaks in the fuse that weren't visible to the naked eye. The comprehensive testing revealed the true cause of the engine overheating warnings and sensor malfunctions. Given the similarity of our issues and that your car recently had service, I would recommend: 1. Get the diagnostic done despite the cost 2. Request specific testing of the thermal management sensors 3. Have them check the engine control module for related fault codes The investment in proper diagnostics saved me from replacing unnecessary parts. While my total repair ended up at 52€, identifying the exact issue prevented much costlier trial-and-error repairs.

Thanks everyone for the insights. After considering the advice, I decided to book the diagnostic service despite the 90€ cost. The symptoms really do sound similar to the sensor issue described, and its better to get it properly checked than risk more expensive repairs later. I will clean the cooling grille and remove the debris buildup first, just to eliminate any potential restricted airflow problems. But given the erratic temperature readings and slow warm-up times, Im now leaning towards an electrical or sensor issue being the root cause. Will update once I get the diagnostic results and know whether its a simple fuse problem like the Polo case or something else affecting the engine cooling system. The comprehensive testing approach makes sense, especially since the check engine light is involved. Right now Im just hoping its not an expensive repair. At least knowing these thermal management issues are somewhat common on VWs is reassuring. Will get it sorted next week and report back on what they find.