I'm having an issue where I have a loss of power and a loss of fuel efficiency. Specifically my hybrid battery gets drained down to red bars when going over 50 mph and when I floor it the engine doesn't downshift or go much faster. I have an average 18mpg. I have had the codes P0171 P2195 (b1 system lean and a/f b1s1 stuck lean) for more than a month with no issues, then 3 days ago the red triangle, (!), Vsc and exlaimation vehicle problem(on MFD) showed with codes p0A0F and P3190(engine failed to start and loss of power). I suspected the ICE water pump because it was leaking and I had no fluid left in resiviour. $450 for Toyota to fix it but didn't resolve issue. They want to replace the A/f sensor for $320 and reprogram ecu for $170 next. I know a faulty a/f can cause lack of power, rough idle and loss of efficiency but Im hesitant because I've had the codes for a month with no issue and I also think the problem could be a bad fuel pump or dirty system because I read in this post about a fellow replacing many different things at many different Toyota shops but the fuel pump was to blame and never threw any codes off. 2006 Prius hybrid system overheats with codes P3190 and P3191 | PriusChat 163k 2004 prius- I cleaned the throttle body with carb cleaner and the MAF with the same (gets 6.28 gm/s at 1215 rpm, 8.84@1323 but 14.1@1900rpm when the lean codes first showed) never replaced spark plugs, replaced pcv valve at 75k, battery is refurb 2014 put 90k miles on it(have another yellowtop just waiting for an adapter)(currently 13.7v) My system is running lean so it's either the o2, which hasn't been a problem for a month after codes were thrown or the fuel pump/system. The o2 sensor was also replaced 3 months ago because the heating circuit was having an error. I'm going to get the o2 sensor replaced and the Ecu reprogrammed but I'm going to ask Toyota to check the fuel pressure first before doing repair. I have techstream if there is anything you could suggest, thanks.
If you already have a 12v maybe replace that to see if it helps anything and you can do it yourself and apparently when going bad it can cause a lot of issues. When you floor it the car never downshifts, it's a CVT trans which means it doesn't change gears like a regular car. It sounds kind of like the hybrid battery just isn't kicking in and providing power along with the ICE. Can you tell with Techstream if the battery is healthy and such? How does it idle? Might also want to have your exhaust pressure tested at a exhaust shop to see if your catalytic converter is clogged. They will kill your ice power and gas mileage when clogged.
They fixed the a/f sensor and it fixed the problem. Ordered spark plugs n shims for the new battery. Thank you