Some 2007-08 Jeep Grand Cherokee and Commander models with 5.7-liter engines may turn on the check engine light and store trouble code P0420 and/or P0430 in computer memory. According to Jeep, the problem affects vehicles built before Jan. 8, 2008, and is attributable to excess electrical noise infiltrating the signal wire of the downstream oxygen sensor. The condition can affect one or both banks of the V8.
Reprogramming the PCM with updated software is the only remedy. For your information, the new calibration installs an "electronic filter" that allows the module to ignore the noise on the signal wire from the sensor. Check with a dealer for the specifics of the flash.
Owners of 2006-10 RAV4, 2008-09 Highlander and 2009-10 4WD Matrix models may come into your store with a complaint of an intermittent no-crank condition. When you get the car in your bay, try moving the shift lever into neutral or from neutral to park, then turn the ignition key again. If the engine now cranks, the park/neutral switch assembly has an internal glitch, says Toyota. Replacing the switch with a new-design, more robust unit, part No. 84540-42010, should put the cranking issue to rest.
Some 2005-08 Odyssey minivans may produce a whining, buzzing or humming sound from the power steering system. Honda says the noise usually occurs after about 30 minutes of driving with the outside temperature between 35 and 40 degrees Fahrenheit and the steering wheel positioned straight ahead. A defect in the power steering reservoir which restricts fluid flow to the pump under the conditions noted is the most likely cause of the trouble. Installing a new-design reservoir, part No. 53701-SHJ-A01C1, H/C 9023672, should eliminate the noise immediately.
"Factory Fixes" is written by Jim DePalma, a 30-year veteran of the auto repair business who has served stints as a service manager, parts manager and ASE-certified technician. His column provides vehicle manufacturers' authentic factory technical service bulletins (TSBs) that have been condensed for easier reading. Mr. DePalma advises that techs always check with a dealer or repair information system for the latest revisions before starting to work on a vehicle. He can be reached via e-mail at [email protected]