NHTSA Complaint #11454937 — 2017 CHEVROLET MALIBU

My 2017 Malibu suddenly had the "check engine" light come on, and a message indicating that a "reduced power mode" had been initiated. I drove the car immediately to the local dealer, who said I needed an appointment to have it checked. I checked the OBD2 codes with my personal meter, which showed a p2138 code, indicating a problem with a throttle body sensor. When I started my car the next morning the MIL light didn't come on. At the dealer I was told they couldn't do anything with the car because the light wasn't on. I pointed out that the failure codes were stored in the ECM, but they said diagnosis wasn't possible with the light off. The service writer indicated the problem was not uncommon on GM cars and that even his wife's car had similar problems. When this occurred I was fortunate to be on a local suburban road where reduced speed was not that great of a problem. Much of the time I am on freeways in several major Midwestern cities where aggressive drivers are packed together. I read a number of complaints on the NHTSA site indicating same complaints from Malibu owners. A sudden reduction of speed in a congested area is a recipe for disaster. The service writer even stated that GM had an extended warranty on the pedal assembly and TPI sensors. But he refused to try and diagnose the issue, unless I brought the car in immediately if and when the MIL light was illuminated, even if I was 500 miles away. As this intermittent behavior is a known and common issue I feel that GM should be compelled to do something to correct these defects before a truly dangerous incident occurs, causing devastating results. But I'm sure that this will go on until misfortune causes those in power to ask. Why didn't somebody do something?