How to Check an EGR Valve on a 1999 Chevy Blazer

The EGR on your 1999 Chevy Blazer looks like a canister that sits on top of the intake manifold. A valve on the bottom of the unit allows exhaust gasses to recirculate back into the combustion chamber through the intake manifold. This helps reduce nitrous oxide, called NOX, emissions. When this unit malfunctions, it can cause serious idle and acceleration problems for your Blazer. To make sure that the Blazer's EGR valve is the problem, you need to troubleshoot it.

Things You'll Need

  • Socket wrench
  • Socket set
  • Phillips-head screwdriver
  • Start the engine and allow your Blazer to warm up to normal operating temperature. When the needle on the water temperature gauge sits in the middle of the gauge, the engine is warmed up.

  • Open the hood and have an assistant rev the engine while you check the plunger movement of the EGR valve. The valve is located behind the distributor toward the back of the engine on the intake manifold. As you rev the engine from 1,500 RPM to 2,500 RPM, you should notice the plunger move. If you don't, then verify that there are no holes in the vacuum line connected to the valve. Also, make sure the line is secure on the valve. Be careful when touching the vacuum lines. Only touch the line and not the valve because the valve will be very hot.

  • Shut the engine off and allow it to cool.

  • Unscrew the hose clamp on the air intake tubing and pull the tubing off the throttle body and push it aside so that you have better access to the EGR valve. You may need to disconnect the idle air-temperature sensor wire in the process.

  • Unplug the EGR valve electrical connector and unbolt the two mounting bolts on the valve. Then, remove the valve.

  • Visually inspect the valve openings for carbon buildup. If there is any carbon buildup and the valve didn't move when the engine was running, clean or replace the valve.