All 2005-07 Acura RL sedans, in addition to 2008 models built from VIN JH4KB16..8C000001 through JH4KB16..8C004681, may turn on the check engine light and store DTC P0401 (insufficient EGR flow) in computer memory.
One possible cause for the problem is carbon buildup at the EGR valve opening in the manifold or on the valve's seat.
Acura says the buildup is due to the unique spray pattern of the fuel injectors. Installing a set of new-design injectors, part No. 16450-R70-A01, with different flow characteristics should help eliminate the concern.
After the new injectors are installed, replace the EGR valve, then clear the trouble code from PCM memory.
"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].