TSBs

Correcting Mazda EGR misfire

Jan. 28, 2025

This bulletin applies to 2016-2021 CX-9 and 2018-2019 Mazda6 vehicles, equipped with SKYACTIV-G 2.5L engines.

Related To: Mitchell 1

If the EGR valve is to be cleaned, replace the gasket P/N PY8V-20-305. If the EGR is to be replaced, use P/N PY8V-20-300.

This bulletin applies to 2016-2021 CX-9 and 2018-2019 Mazda6 vehicles, equipped with SKYACTIV-G 2.5L engines. Some vehicles may exhibit an occasional rough idle accompanied by DTC P0300:00 (random misfire) due to the following:

1. While closing the EGR valve, carbon deposits may be pinched at the valve seat, preventing the valve from closing completely.

2. The closed position of the EGR valve is learned improperly as it is not equipped with a position sensor.

3. While idling, the EGR gas improperly mixes with fresh air through the EGR valve that is not closed properly.

4. Misfire occurs.

To eliminate the concern, reprogram the PCM. The control software of the PCM has been modified to force the learning of the closed position of the EGR valve when a misfire is detected at idle.

If the EGR valve is to be cleaned, replace the gasket P/N PY8V-20-305. If the EGR is to be replaced, use P/N PY8V-20-300.

About the Author

Mike Mavrigian | Motor Age Editor

Mike Mavrigian has written thousands of automotive technical magazine articles involving a variety of specialties, from engine building to wheel alignment, and has authored more than a dozen books that crisscross the automotive spectrum. Mike operates Birchwood Automotive, an Ohio shop that builds custom engines and performs vintage vehicle restorations. The shop also features a professional photo studio to document projects and to create images for articles and books.