High internal engine temperatures lead to the formation of oxides of nitrogen (NOx) that are smog forming pollutants. The exhaust gas recirculation (EGR) system is used to lower combustion temperatures and reduce NOx emissions. This is accomplished by reintroducing exhaust gases into the engine via an EGR valve.
Some EGR valves are vacuum controlled, some are completely electronic and some are a combination of the two. The hybrid systems often use a remote-mounted EGR control solenoid which is used to apply vacuum to the EGR valve itself. The solenoid is directly controlled by the powertrain control module (PCM).
The typical symptoms of a failed EGR control solenoid include stalling, surging, rough idle, increased emissions, and an illuminated check engine light.
Part 1 of 3: Locate the EGR control solenoid
In order to safely and efficiently replace your EGR control solenoid, you will need a couple of basic tools:
Step 1: Locate the EGR control solenoid. The check valve is generally found mounted to the intake manifold or firewall.
Part 2 of 3: Remove the EGR control valve
Step 1: Disconnect the negative battery cable. Disconnect the negative battery cable and set it aside.
Step 2: Disconnect the solenoid vacuum hoses. Disconnect the vacuum hoses by carefully sliding them off the connections.
Step 3: Remove the electrical connector. Remove the electrical connector by pushing down on the tab and sliding it off.
Step 4: Remove the retaining fastener. Remove the solenoid retaining fastener using a ratchet or wrench.
Step 5: Remove the solenoid. Remove the old EGR control solenoid and keep it aside.
Part 3 of 3: Install the air injection check valve
Step 1: Mount the new solenoid. Mount the new solenoid in position.
Step 2: Install the fasteners. Reinstall the fasteners and tighten them until they are snug.
Step 3: Reinstall the electrical connector. Put the electrical connector back on.
Step 4: Reinstall the vacuum hoses. Put back the vacuum hoses that you had removed earlier.
Step 5: Reconnect the negative battery cable. Reconnect the negative battery cable and tighten it down.
That’s it - you now have a new EGR control solenoid! If you’d prefer to leave this task to the professionals, YourMechanic offers an expert EGR control solenoid replacement service that you can rely on.
This article originally appeared on YourMechanic.com as How to Replace an Exhaust Gas Recirculation (EGR) Control Solenoid and was authored by Mia Bevacqua.