ENGINE LOST ALL POWER, CAUSING MULTIPLE NEAR REAR END COLLISIONS. DIAGNOSTICS INDICATED IN CHRYSLER SERVICE MANUAL POSTED "55" (END OF MIL CODES) INDICATING NO FAILED COMPONENTS. SERVICE STATION REPLACED O2 SENSOR AND CLEANED SUBSEQUENT IMPACTS TO FUEL INJECTORS. PER CHRYSLER SERVICE MANUAL, O2 SENSOR FAILURE CODE "21" SHOULD HAVE BEEN INDICATED FOR SUCH FAILURES, THUS AFFORDING A WARNING TO DRIVER OF FAILED COMPONENT.*AK