This Preliminary Information communication provides information to the technician about vehicles that may have a Malfunction Indicator Lamp on. Technician may find Diagnostic Trouble Code P01285 and or P0171. Technician will need to use published Service Information diagnostics first. Technician will update the Engine Control Module with the latest calibration in Tis-2-Web if published Service Information diagnostics do not resolve the concern. If the calibration did not repair the concern inspect the engine for oil leaks and insure the oil fill cap is properly closed. Technician will also use the CH-44175-1 handheld tester to test the ethanol content of the fuel. Technician should also inspect for unmetered air/vacuum leaks by using the Evaporative Emissions System smoke machine to induce smoke into the engine, exhaust, and air intake system as outlined in the latest version of PIP4925. Technician should inspect the air filter condition to ensure that it is a factory filter and that none of the pleats are damaged and the inside of the air cleaner opening before the Mass Air Flow sensor for any sign of casting flash. If the concern is currently happening while at a hot idle, plug all vacuum lines.
