Techniques are described for use by an implantable medical device equipped to use trim values, which allow the device to continue to use trim values despite certain memory errors such as parity errors. Briefly, optimal trim values are stored within RAM. Nominal trim values are stored within ROM. Device functions are then performed using the trim values stored within RAM. If an error is detected indicative of possible corruption of RAM, then the trim values from ROM are loaded into RAM to enable continued operation of the device using the nominal trim values despite the error. In a preferred implementation, the optimized trim values are initially stored at two separate locations within RAM. A procedure is described herein for allowing the device to continue to use the optimized trim values following a device reset if no parity error is detected. If a parity error occurred, the device instead uses the nominal trim values from ROM.