Q: I have 2000 E320 Mercedes Benz and code p1491 came on with Check Engine Light.

Hey there. Your question isn’t entirely clear, but I can address the code you have listed. The P1491 code has to do with your A/C system. Specifically, the high side of the A/C is too high. This could be for a number of reasons. Most commonly it will be because the cooling fans on the condenser are not turning on. But this could be result of an over filled refrigerant in the system.

It does say there is no blockage. I assume this means there is no blockage in the system, which could cause high pressure in the high side. A blockage would also cause the low side to be very low and a few other more technical details that I won’t go into. With this information, I would first be looking at the cooling fan operation.

If you should need some more assistance with this, you may want to have another expert inspect the Check Engine Light more thoroughly in order to have the precise repairs done.