Some owners of 2007-2015 Mazda CX-9 vehicles may note a check engine light on while driving. If DTCs P2A04:00 (HO2S LH circuit range/performance) and/or P2272:00 (HO2S LH signal stuck lean) are found, inspect the C-34 connector for engine oil contamination (connector on emission/injection harness).
If oil contamination is not found, diagnose DTCs according to instructions on MGSS online. If oil contamination is found on the C-34 connector, inspect the engine oil pressure switch for external leaks. If a leak is found, replace the oil pressure switch. Clean the C-34 connector and harness of oil.
Inspect the related O2 sensors according to instructions found on MGSS online. If the related O2 sensors are not operating correctly, replace as needed. Clear the DTCs and test drive to confirm the repair.