Some 2007-08 XL-7 SUVs with rear air conditioning systems may illuminate the check engine light and store trouble code P0128 (engine coolant temperature below thermostat regulating temperature) in the PCM.
Suzuki said the condition usually occurs when the ambient temperature is below freezing and is most likely due to the PCM being unable to figure out that extra warm-up time is required with the greater coolant capacity of a rear HVAC system.
Reprogramming the module with updated software is the only surefire fix. Check with a dealer for the specifics of the new calibration.
"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]om.