Massive amount of exhaust and heater blowing cold air

Hello, first, I would focus on what is preventing the heat from your vehicle. If your engine is not reaching proper operating temperature, then you will not only achieve heat out of your heater, but your engine will not operate efficiently and properly. You should be able to monitor coolant temperature and many other engine parameter data with a good diagnostic tool compatible with Nissan. You may learn much from this. You may have a string of codes related to fuel control, evaporative emissions and EGR operation, but I would probably still focus my attention on engine temperature before even going to those places, as none of those places will affect heat and operating temperature. Naturally, it is all important though.

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