Ford P1091 OBD-II Trouble Code Definition: P1091 Pre-Catalyst Fuel Trim Too Rich Bank 1 P1091 Ford OBD-II Trouble CodeDescription: Causes – Low fuel pressure– Large vacuum leak on engine– Faulty Mass Air Flow (MAF) sensor– Faulty Ignition– Faulty fuel injector Symptoms – Engine Light ON (or Service Engine Soon Warning Light) […]