What does excessively high temperature difference between EGP inlet and outlet mean?
3 Answers
An excessively high temperature difference between EGP inlet and outlet generally refers to an excessive difference between atmospheric temperature and exhaust gas outlet temperature. Below is an introduction to EGP knowledge: Introduction: "EGP" refers to the diesel electronically controlled common rail National IV exhaust treatment component, commonly known as the muffler with catalytic converter. The exhaust treatment unit is equipped with 2 catalytic converter temperature sensors and 1 NOX sensor. The two temperature sensors are located at the inlet and outlet of the catalytic converter, referred to as inlet and outlet temperature sensors respectively. Function: Its main purpose is to detect the temperature of exhaust gases from the engine. When the detected exhaust temperature exceeds 200°C, the engine's electronic control unit receives this signal and sends corresponding execution commands to the metering injection pump to control the nozzle to inject a certain amount of urea solution into the exhaust pipe.
I heard the mechanic mention this last time I got my car repaired. A too large temperature difference between the inlet and outlet air of the car's air conditioning evaporator is not a good sign. Generally, if the temperature difference exceeds 15 degrees, you should be alert. The most common issue is the expansion valve getting stuck at the minimum opening, preventing refrigerant flow and causing a sudden drop in outlet temperature. Alternatively, the condenser might be dirty, affecting heat dissipation efficiency and preventing the inlet temperature from dropping. Another possibility is the evaporator frosting up and getting blocked, which would definitely cause a large temperature difference since air can't pass through. If this problem isn't addressed promptly, not only will the air conditioning blow colder and colder, potentially harming the engine, but the evaporator working at excessively low temperatures for a long time is also prone to icing and pipe bursts. Imagine how dangerous it would be to suddenly lose cooling on a highway in summer.
As a veteran taxi driver with 15 years of experience, I've encountered this issue several times. Simply put, it's when your AC vents become much colder than the intake, feeling like an ice cellar. The root cause is either overcharged refrigerant where the compressor forces liquid refrigerant directly into the evaporator, or an aging blower motor with insufficient RPM that can't carry away the cold air. The most annoying scenario is when a faulty temperature sensor sends wrong data, tricking the ECU into overcooling. My advice is to immediately increase fan speed when you notice scalp-freezing AC, then visit an auto repair shop ASAP for refrigerant pressure testing – delaying could lead to frozen and cracked AC lines.
