2005 Kia Sportage P0150, P0160, P0172 O2 Sensor Bank 2 Sensor 1 Fault - Yellow Residue Detected
My 2005 Kia Sportage LX with a 2.7L V6 engine (mileage: 230,000 km) is currently displaying OBD-II diagnostic codes P0150, P0160, and P0172. These codes relate to issues with the oxygen sensor in Bank 2, Sensor 1. After performing a visual inspection of the O2 sensor and its wiring, I observed yellow residue on the sensor tip. Yellow discoloration is typically indicative of sulfur contamination, which can degrade sensor performance. I have already replaced several components as part of troubleshooting: MAF sensor, CKP sensor, intake manifold gasket, air filter, ignition coils, and spark plugs (iridium), along with all four oxygen sensors (Bosch brand). Despite these replacements, the codes persist. Attached are photos showing the yellow residue on the O2 sensor tip for reference: IMG_0486.JPG (50.8 KiB) and IMG_0485.JPG (50.08 KiB). I am seeking expert advice to properly diagnose and resolve these persistent OBD-II codes, particularly focusing on whether sulfur contamination or wiring issues are the root cause.
P0150 indicates a circuit issue with the oxygen sensor in Bank 2, Sensor 1. Ensure the sensor signal is properly grounded and that there are no open or shorted circuits in the wiring harness. Check for corrosion or physical damage to the connector as well.