Mazda CX-9 2016–2021 — technical service bulletin
Bulletin 01-001-21-3761a · NHTSA communication 10199713 · issued Jul 26, 2021
Technical service bulletin
communication type
Engine and Engine Cooling
component
2016–2021
model years
8
vehicle entries
Official summary
Some vehicles may exhibit an occasional rough idle accompanied with DTC P0300:00 (Random misfire) due to the following: 1. While closing the EGR valve, carbon deposit etc. pinched at the valve seat prevents 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 this concern, the control software of the PCM has been modified (for service) to force the learning of the
Vehicles covered
What a TSB means. Technical service bulletins are repair guidance manufacturers send to dealers — they are not recalls, and repairs are not automatically free (warranty extensions are an exception worth checking). The full document is available via NHTSA’s vehicle lookup.