VW Fox Cooling System Issues Causing Start-Up Delays

I had almost the exact same issue with my 2012 VW Polo diesel last winter. As someone with basic experience working on cars, I initially thought the radiator grille or cooling system was the culprit too. After checking the obvious parts of the thermal management system myself, I took it to my regular workshop. Turns out it was just a blown fuse controlling the temperature sensors, causing incorrect readings and triggering the check engine light. The whole repair including diagnostics cost 52€. The symptoms match yours exactly, unreliable temp gauge, slow warm-up, and warning lights. The workshop explained that a faulty fuse can make the cooling system sensors report incorrect values, even though the actual automotive cooling components are working fine. Before jumping to conclusions about the radiator grille, could you share: Are you getting any specific error codes? Does the temperature eventually stabilize? Have you noticed any coolant leaks? When was your last cooling system service? This information would help determine if you are dealing with the same electrical issue or if there might be a different problem with your cooling system components.

Last service was done at 35000km and everything was fine. Since then, the check engine light keeps coming on intermittently. The error code reader shows P0128 which points to cooling system performance issues. The temperature does stabilize after about 20 minutes of driving, but takes much longer than it used to. No visible coolant leaks found, but I noticed the coolant level dropping slightly over the past month. The radiator blockage theory makes sense since I often park under trees, but I am hoping it is just a minor issue like the fuse you mentioned.

Good to hear back from you regarding your VW Fox. After reading about your error code P0128 and coolant level drop, I am less convinced it is the same fuse issue I experienced with my Polo. While restricted airflow from a blocked radiator grille could cause these symptoms, there are a few concerning differences: The gradual coolant loss suggests we might be dealing with a small leak in the cooling system rather than just a blocked grille or sensor issue. When my car had the fuse problem, the coolant level remained stable. P0128 specifically indicates the engine is not reaching proper operating temperature within the expected timeframe. This could be caused by: Faulty thermostat (most common with this code), Coolant leaks reducing system pressure, Radiator blockage restricting proper heat exchange, Damaged water pump Since you mentioned parking under trees, checking for debris in the radiator grille is still worth doing. But given the coolant loss, I would recommend having the entire cooling system pressure tested to locate any potential leaks. The repair costs will vary significantly depending on the actual cause, from 50€ for a thermostat to several hundred for a water pump replacement. Would strongly suggest getting this checked soon before any car overheating issues develop.

Your feedback is really helpful. I checked for debris in the radiator grille yesterday and while I found some leaves, removing them did not improve the situation. The coolant loss is definitely concerning, I measured it again today and noticed it dropped another few millimeters. I will take it to the workshop next week to get the cooling system pressure tested. Since engine overheating could cause serious damage, I do not want to risk driving it too much before getting it properly diagnosed. The thermostat replacement cost you mentioned sounds reasonable at 50€, but I am hoping it is not the water pump as that would be quite expensive to fix. Will any automotive cooling system specialist be able to perform the pressure test, or should I look specifically for a VW certified workshop? I want to make sure they can properly diagnose restricted airflow versus internal leaks or other potential causes of the engine cooling problems.