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How to Clean an EGR Valve on a Miata

by Eric W. Thompson

The EGR valve in your Mazda Miata reduces the nitrogen oxide emissions produced by your engine. It significantly diminishes harmful emissions by recirculating a fraction of the exhaust back to the engine cylinders and removing combustible matter from each cylinder. As buildup accrues on the EGR valve over time, your Miata emits increasing levels of dangerous chemicals during operation. Removing the EGR valve and cleaning it is a fairly simple and easy task, so you can perform it yourself and save the money needed for a mechanic.

Step 1

Disconnect the negative battery cable using a ratchet and socket, locate the EGR valve on the passenger side of the engine near the intake manifold and the throttle body, then pull the electrical cable and the two vacuum hoses from the EGR valve using your hands.

Step 2

Unbolt the EGR valve using the ratchet and socket with an extension, then pull the gasket from the EGR valve mount. Spray the surface of the mount and the EGR valve liberally with carbon cleaner and allow the solution to sit for a few minutes before wiping it off with a rag.

Step 3

Spray the hoses, inside and outside, down with carbon cleaner. Wipe the outside of the hose down with a clean rag, then wipe the inside of the hose down using long cotton swabs.

Step 4

Inspect the EGR valve, mount and hoses to be sure that all the carbon has been removed.

Allow the valve and hoses to dry, then follow the previous steps in reverse to complete the job.

Items you will need

  • Ratchet and socket
  • Ratchet extension
  • Carbon cleaner, compatible with your vehicle's catalytic converter (check manufacturer's specifications)
  • Rag
  • Long cotton swabs
  • Gasket sealer
  • Replacement gasket
  • Replacement valve

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