Exhaust Heat RECIRCULATION System Circuit [11/2016 - ]: Description

In the exhaust heat recirculation system, coolant is warmed up using exhaust gas heat to accelerate engine warm-up time, enhancing fuel efficiency and heater performance.

The heat recirculator is positioned in the center exhaust pipe assembly after the catalyst. Coolant from the engine flows around the heat recirculator and then returns to the engine. If the engine is started while the engine is cold, the exhaust pipe gas control actuator rod is contracted and the exhaust flow control valve is closed, routing the exhaust gas around the heat recirculator to warm up the coolant.

After the engine coolant temperature rises and the engine has warmed up, the heat of the coolant expands the thermostat and the exhaust pipe gas control actuator rod extends. This opens the exhaust flow control valve to switch to the normal exhaust gas path.

The exhaust flow control valve can also be opened by exhaust gas pressure to prevent insufficient acceleration performance when the engine is cold. In addition, to monitor the engine coolant temperature, a temperature switch is provided between the engine and the heat recirculator. When the engine coolant temperature is normal, the temperature switch is closed (on). If the engine coolant temperature is excessively high (overheating), the switch opens (off) and the needle of the water temperature receiver gauge in the combination meter assembly indicates above HI to inform the driver of the malfunction and DTC B1503 is stored.

Refer to DTC B1503: Exhaust Heat Management Warning Detected [11/2016 - ] .

Fig 1: Exhaust Heat Recirculation System Function

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