Hi. I have 2001 Prius with 183 k. Few days ago when I start my car I saw red or yellow ! in triangle and on multi Warning (pictures). I start and stop car for 3 times and it disappear, but check engine light stay on. My friend scan it, it shows 3 codes: P3191, P0420 and P1455. After next few days check engine light turn off. Few month ago mechanic told I should to change engine computer, he told me driving with this malfunction is safe but comp can show some stupid (false) messages. I didn't change computer because dealer want more than 1000$ and I don't have it for now. What do you think, is those codes are real malfunction or crazy comp? Next thing is my MPG go down, now it is between 37 and 39, in Chicago is cold between 5 to 35 F. My Toyota never show better than 44 MPG, what's wrong? Why it can't be 50 MPG, what I have to do to have smaller fuel consumption. Thank you for help. Happy Holidays and Great New Year!!!
First, understand that some Toyota codes won't appear on generic scanners, so we may not know all. P0420 refers to low catalyst efficiency. Could be an O2 sensor problem, or more fundamental. P1455 is small vapor leak of fuel atnk. Could be a loose gas cap. P3191 is the engine no start or slow start. We often suggest cleaning the throttle plate / fuel indiction system. Or, new spark plugs. The computer you mention should have the number 89661-47054. If yours does, a new computer may not help. If lowe ## in last two digits then yo ucould buy new from Toyota or salvage takeout from several sources. Work on these and make sure your 12 volt battery is performing well. Then we can fix your fuel economy, maybe. For that I'd start with tires and suspension alignment.
