Hyundai Tucson: Crankcase Emission Control System

Hyundai Tucson - Fourth generation (NX4) - (2020-2023) - Workshop Manual / Emission Control Syste / Crankcase Emission Control System


  1. Crankcase pressure regulating valve (PRV)
  2. Breather hose
  3. Air flow
  4. Intake manifold
  5. Cylinder block
  1. Blow-by gas flow
  2. Blow-by gas inflow to the cylinder head cover throungh the cylinder block & head & chain cover
  3. -1 In the partial load area, blow-by gas inflow to the intake manifold through the PRV valve which in the head cover.
  1. -2 In the full load area, blow-by gas inflow to the intake hose through the PRV valve which in the head cover.
  2. Mix of intake hose and blow-by gas. Blow-by gas is circulated by the (3)-1, (3)-2 procedure.
  3. Combustion the air-flow mixture.


Pressure Regulating Valve (PRV) is installed to prevent the over pressure of combustion gas through the piston ring and onto the crankcase.

Operation Principle

Operation Principle

Diaphragm component part

Diaphragm component part



  1. Remove the cylinder head cover.

(Refer to Engine Mechanical System - "Cylinder Head Cover")


  1. Install in the reverse order of removal.

Description and Operation


Emissions Control System consists of three major systems.

  • Crankcase Emission Control System prevents blow-by gas from releasing into the atmosphere. This system recycles gas back into the intake manifold (Closed Crankcase Ventilation Type).
  • Evaporative Emission Control System prevents evaporative gas from releasing into the atmosphere.

    This system burns gas at appropriate engine operating condition after gathering it in the canister.

  • Exhaust Emission Control System converts the three pollutants hydrocarbons (HC), carbon monoxide (CO), and oxides of nitrogen (NOx) into harmless substances by using the 3-way catalytic converter.


      Evaporative Emission Control System

      Evaporative Emission Control System - Description

    Description The Evaporative Emission Control System prevents fuel vapor stored in fuel tank from vaporizing into the atmosphere. When the fuel evaporates in the fuel tank, the vapor passes through vent hoses or tubes to a canister filled with

      Evaporative Emission Control System - Removal

    Removal WARNING Be careful not to damage the parts located under the vehicle (floor under cover, canister, fuel tank) when raising the vehicle using the lift. (Refer to General Information - "Lift and Support Points") Turn


     Pressure Side Impact Sensor (P-SIS)

    Disconnect the batteiy negative terminal. WARNING After disconnecting the cables, wait at least 3 minutes. Remove the front door trim. (Refer to Body - "Front Door Trim") Disconnect the connector (A) from the pressure side im

     Wiring Precautions

    SRS wiring can be identified by special yellow outer covering Observe the instructions described in this section. Never attempt to modify, splice, or repair SRS wiring. If there is an open or damage in SRS wiring, replace the harness.