Isuzu NPR - P20C9 + P2203 codes POSSIBLE fix

P20C9 is just the warning light, but P2203 is the culprit. The cause on this truck is a corroded wire one of the NOX sensors, but that may not be the case on yours. This is just one easy thing to check visually. The NOX sensor part number is "89824 65060". The bolts to get the module off are 10mm and the sensor itself is 22mm but 7/8" works too.