Q: Glow plug warning light even after changing glow plugs

The glow plug warning light doesn’t necessarily mean the car needs glow plugs. The engine control unit turns on the light to alert you that it has detected a fault in some component of the system, not just the glow plugs. The car needs to be scanned with the appropriate diagnostic equipment to read the codes that have been stored. As for the glow plugs, It may have been a mistake to install the glow plugs that you bought. The engine management system is very sensitive to subtle changes in equipment, so if the glow plugs were not designed specifically for your engine, they may cause your car to present a code. That code will now be stacked up in line behind whatever other codes are already present. By contacting Your Mechanic, you can have a technician with the right diagnostic equipment come to your home or office and read the codes in your car and advise you on what needs to be done.