I have a 2020 GMC Sierra 3500 AT4 and I've been towing a 30ft fifth wheel for 3 months now. Usually when I fill up on diesel it says I can go about 386 miles. The last two times I have filled up it said I could only go 281 miles. I can't figure out the reason why except that it needs a new particulate matter sensor. Would this really cause the mileage to drop so much?
